CA1150055A - Compressed gaseous materials in a contained volume - Google Patents

Abstract

ABSTRACT

The invention relates to hollow inorganic film forming material (preferably glass) microspheres of substantially uniform diameter of 200 to 10,000 microns and of substantially uniform wall thickness of 0.1 to 1,000 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature. The micro-spheres are free of latent solid or liquid blowing gas materials or gases and the walls of the microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles. The microspheres may be filamented and connected to each other by filament portions which are continuous with the microspheres and are of the same inorganic film forming material.

Description

s This application is a division of Serial No. 334,639, filed August 27, 1979.
The present invention relates to hollow microspheres formed from inorganic film forming materials and having a gaseous material under high pressure within the contained volume of the microsphere. Preferably, the inorganic film forming material is glass and the invention is hereinafter described in that context.
The present invention also relates to hollow glass micro-spheres having a gaseous material under high pressure within the contained volume of the microspheres and having a metal coating deposited on the inner wall surface of the microsphere.
The present invention also relates to the use of the hollow glass microspheres and the hollow glass microspheres having a transparent or reflective coatiny deposited on the inner wall surface thereof for the handl:ing and storage of gaseous materials under high pressure. The hollow glass microspheres of the present invention, depending on their diameter and their wall thickness and the particular glass composition from which they are made, are capable of withstanding very high internal gas pressures. The hollow glass microspheres are resistant to high temperatures, stable to many chemical agents and weathering conditions. These characteristics make them suitable for the handling and storage of gaseous materials generally and particular-ly for toxic and corrosive gaseous materials at high pressures.

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~s~rss The hollow glass microspheres of the present invention, depending on their diameter and their wall thickness and the particular glass composition from which they are made~ are capable of withstanding relatively high internal pressures and/or external weight.

BACKGROU`~D OF THE I~VEMTION

In recent ~lears, the substantial increases in the costs o~ handling and storage of gaseous macerials has created an incentive for improved methods of handling and storage of gaseous materials. The manufacture of highly to~ic, corrosive and/o~ poisonous gases or waste gases has created a serious problem of handling and storage of ~he materials and/or of disposal of unwanted materials. Environmental problems have been created by che need to find adequate and safe means or handling and storing radioactive atomic energv fuel and fuel waste materials.
There has also developed a need in inertial con-finement fusion systems ror a means of obtainingunder high pressure small target fuel materials contained in a material from which they do not difuse or do not dif~use at a high rate.
Hollow glass microspheres have been used as micro-containers ~or mixtures of hydrogen isotope gases which were used as laser targets to obtain or attempt to obtain thermonuclear reac~ions.
However, the method of making the glass micro-spheres, the microspheres themselves and tne method or ~illi~g the microspheres have several disadvan~ages. The commerciallv available gl2ss microspneres are made bv grinding glass ~o a desired particle size and heating the ground particles to a high temperature to "blow" the 3~ particles into hollow glass microspheres. The "blowing" gas in the known procedure is gas that had been trapped in the glass during the manufacture of the glass. The microspher~s that are obtained are of non-uniform size, shape and wall thickness and have contained in the walls thereof small trapped gas bubbles.

~ ~3~ ~ 5 ....
The microsphere3 that are to be used as laser ~uel targets must be of uniform size and wall ~hickness as a consequence of whicn only a very small proportion of the comme-ciall~ produced microspheres can be used, for e~ample, one in a million. Further, the gas used to blow the micro-spheres mus~ be purged and the desired h~Jdrogen . isotope gases introduced into the microspheres.
The method now used to introduce the hydrogen isotope gases into the microspheres involves relatively nigh temperature and very high pressure gas permeation or diffusion techniques. The hydro-gen gases under high pressure are made to slowly diffuse through the "pores" of the glass micro-sphere and displace the internal gas in the micro-sphere. Cooling the microspheres and maintaining the microspheres under refrigeraticn can sub-stantially reduce loss of the gases thus co~l-pressed into the microspheres. Over a long period of time, however, signi~icant amounts of the compressed gases dirLuse out of the micro-spheres wnich results in a loss of the hydrogen gases fuel and efficiency of the thermonuclear ~ eaccion.
.~ S The known methods ror produci~g nollow glass mic-osphere~ have not been successful in producing microspheres of relativelv unifor~
si~e or uniform thin walls which makes it very dirricul~ to~produce hollow glass microspheres or controlled and predictable characteristics and quality and strength or at low cost which are capable of containing elevated internal gas pressures without significant pressure loss.

An inherent problem with the known method of ma~ing microspheres is that since the glass micro-spheres had to be su~ficiently porous tc allow the gases to diffuse into the mîcrospheres some of the pressurized gases will diffuse ou~ of the micro-spheres. Another problem is that the method is limi~ed to the use of low molecular weight gases for diffusing into the microspheres. There is the additional problem that the prior art pressurized microspheres are required to be maintained under re rigeration to minimi2e outward diffusion of the oressurized gases.
A serious problem that e~ists with the known mechod is that t:ne small gas bubbles that are trapped in the walls of the microspheres during manufacture of the microspneres weakens the microspheres, thus limiting to some exten~ the amount oE hydrogen isotope gases or other gases, that is the pressure of the gases, that can be coneained in the microspheres.
The ~nown methods of producing hollow glass microspheres, for e~Yample t as disclosed in the Veacch e~ al U.S. Patent 2,797,201 or Beck et al U.S. Paten~ 3,365,315, involve disoersing a liquid and/or solid gas-~hase ?recursor material in the gla-~s material to be blown to form the microspheres. The glass material containing the solid or liquid gas-phase precursor enclosed therein is then heated to convert the solid and/or liquid gas-phase precursor material into a gas and is further heated ~o expand the gas and produce ~he hollow glass microsphere con-taining therein the expanded gas. This proce~s is~ understandably, dif~icult to control and of .~ _ _ _ . . . _ -s necessity, i.e. inherently, produces glass microspheres of random size and wall thickness, microspheres with walls that have sectlons or portions of the walls that are relatively thin, walls that have holes, small trapped bubbles, trapped or dissolved gases, any one or more of which will resul~ in a sub-stantial weakening of the microspheres, and a subs~antial number or proportion of microspheres which are not suitable foruse which must be scrapped or recycled.
Also, the relatively high cos~ and the relatively small size of the prior art microspheres has limited their use.
Further, the known methods fo~ pro-ducing hollow glass microspheres usually rely on high sod~ content ~lass compositions because of their relatively low melting temperatures. These glass compositions, however, were found to have poor long term weathering characteristics and a relatively high mean atomic number.
In addition, applican~ round in his initial attempts to use an inert blor.~ing gas to blow a thin molcen glass ~ilm to form a microsphe~e thac the rormation of the ~lass microsphere was extremely sensitive and that unstable glass .. . . . .... . . .. .. ... . . . .

films were produced which burst into minute sprays of droplets before a molten glass film could be blown into a microsphere and detached from a blowing nozzle. There was also a tendency for the molten glass fluid to creep up the blowing nozzle under the action of wetting forces. Thus, the initial attempts to blow hollow glass microspheres from thin molten glass films were unsuccessful.
In addition, in some applications, the use of low density microspheres presents a serious ~roblem because chey are difficult to handle si.nce thev are readily elutriated and tend to blow aboue. In situations of this type, the filamented microspheres of the present invention provide a convenient and safe method of handling the microspheres.

.1~51~ ~5S

BRIEF DESCRIPTION OF THE INVENTION

According to the present invention, there are provided hollow inorganic film forming material microspheres of substantially uniform diameter of 200 to 10,000 microns and of substantially uniform wall thickness of 0.1 to 1,000 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.
According to a further aspect of the present invention, there are provided filamented, hollow inorganic film forming material microspheres having a diameter of 200 to 10,000 microns, having a wall thickness of 0.1 to 1,000 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same inorganic film forming material from ~hich the microspheres are made.
Preferably the inorganic film forming material is glass and, as stated above, the invention is discussed herein in that context.
The microspheres are made from a glass composition selected for the particular gaseous material to be contained therein. ThP
microsphere can also be made to contain a metal coating deposited on the inner wall surface of the microspheres. The metal coating, depending on its thickness, can be transparent or reflective.

_ ~ _ S

The glass microspheres of the present invention can be used to handle and store gaseous materials, generally such as oxygen, hydrogen, nitrogen and carbon dioxide; toxic, corrosive and/or poisonous and/or waste gases and radioactive atomic energy fuel material - 8a -r3~,55 and fuel waste material and in the handling and storage of unstable gases. ~he microspheres can be used in the manufacture of laser fuel targets for hydrogen fusion reactor research and reactors.
An advantageous use of the hollow microspheres is in the manufacture of laser ~uel targets for inertial confinement fusion systems and reactors.
Par~icular and advantageous uses of the hollow glass microspheres are for the storage of a~omic fuel waste materials and the ~anufacture of laser ruel targets ~or inertial confinement fusion systems and reactors.
The hollow glass microspheres of the present invention are preferably made by forming a liauid film of molten glass across a coaxial blowing nozzle, applying the blowing gas at a positive pressure on the inner surface o the glass film to blow~
the ilm and Eorm an elongated cylinder shaped liquid film of molten glass which is closed at its outer end. The hollow glass microspheres of the present invention can also be made by using as the blowing gas a gas containing a metal vapor, dispersed metal particles and/or an organo metal co~pound. .~ balancing but slightly lower gas p.essure is provided :in the area oE
~ the blowing nozzle into which the elongated -; cylinder shaped liquid ~ilm is blown.
` A transverse jet is used to direct an inert entraining fluid over and around the blowing nozzle a~ an angle to the axis of the blowing nozzle. T~e entraining fluid as it passes over and around the blowing nozzle and the elongated cylinder ~luid dynamically induces a pulsating or fluctuating pressure field at the opposite or lee side o~ the blowing nozzle . . .

in the wake or shadow o~ the blowing nozzle.
The fluctuating pressure field has regular periodic laceral oscillations similar to those of a flag flapping in a breeze. The transverse jet entraining fluid can also be pulsed at regular intervals to assist in controlling ~he size of the microspheres and in separating the microspheres from the blowing nozzle and the distance or spacing between micro-spheres.
The entraining fluid envelops and actsasymmetrically on the elongated cylinder and causes the cylinder to flap, fold, pinch and close-off at its inne- end at a point pro~ima~e to the coaxial blowing nozzle. The continued movement of the entraining fluid over the elongated cylinder produces fluid drag forces on the cylinder and detaches the elongated cylinder fro~ the coaxial blowing nozzle to have it fall from the blowing nozzle. The surface tension ~orces of the molten glass act on the now free falling elongated cylinder and cause the cylinder to seek a minimum su~face are~ and to form a spherical shape.
Quench nozzles are disposed below and on either side of the blowing nozzle and direct cooling fluid at and into contact with the molten ~lass microspheres ~o rapidly cool and solidify ~he molten glass and ~orm a hard, smooth hollow glass microsphere. Where a metal vapor in ad~ixture wi~h a blowin~ gas is used to blow the microspheres, the quench fluid cools and condenses the metal vapor and causes the metal vapor to deposit on the inner wall surface of the microsphere as a transparent ;;r~d~55 metal coating or a thin refleccive metal coating.
The microspheres can be made from glass compositions selected for their desired optical and chemical properties and for the particular gaseous material to be contained therein.
T.~ere a gas containing dispersed metal particles is used to blow the microspheres, a metal layer is deposited on the inner wall surface of the microsphere as a thin metal coating. Whêre a gaseous organo metal compound is used to deposit the metal laver, a gaseous organo metal compound is used as or with the blowing gas tO blcw the microspheres. The organo metal compound can be decomposed just prior to blowing the microspheres or after the microspheres are formed by, for e~ample, subjectin~ the blowing gas or the microspheres to heat and/or an electrical discharge means.
The filamented microspheres are preferably made in a manner such that they are connected or attached to each other by a thin continuous glass fila-ment. The filamented microspheres also assist in handling and preventing sca~cering of micro-spheres, particularly r~here very s;nall diameter ~5 microspheres or low densiry microsp'neres are produced.

-THE ADVANT.~GES

The present invention overcomes many o~ theproblems associated wi~h prior attempts to pro-duce hollow glass microspheres containing and/or to con~ain gaseous materials at high pressures.
The process and apparatus of the present invention allows the production of hollow gl2ss microspheres having ~redetermined diameters, wall thicknesses, strength and resistance to chemical agents and weathering and gas permeability such that imDroved systems can be designed, manufactured and tailor made ~or storage and handling of contained gases to suit a particular desired use. The diameter, wall chickness and unirormity and the strength and resistance to chemical agents characteristics or the microspheres can be determined by carefully selecting the cons~ituents of the glass composicion and controlling the blowing gas pressure and temperature and viscosity and thickness of the molten glass film from wnich the microspheres are fonned. The inner volume o~ the microspheres contains at high pressure the gaseous material used to Slow the micro-sphere which is to be ma:intained with the micro-2S sphere. The hollow glass microspheres can havea transparent or a reflective metal coating deposited on the inner wall surface of the microsphere. The reflective metal coating re~lects light and reduces the possibility of photochemically induced chemical reactions occurring in ~he high pressure gaseous materials contained within the microspheres~

iO55 The attached drawings illustrate exemplary forms of a method and apparatus ~or making microspheres according to the invention for use in compressing gases at high pressure in.a contained volume.
The Figure 1 of the drawings shows in cross-section an appara~us having multi?le coa~ial blowing nozzle means fo~ supplying the gaseous materials for blowing hollow glass micro-spheres, a transverse jet providing an entraininCrluid to assist in the formation and de~achmenc or the microspheres from tne blowing nozzles, and means for supDl~Jing a quench fluid to cool the microspheres.
The Figure ~ of the drawings is an enlarged detailed c~oss-section of the nozzle means of appa~atus shown in Figure 1.
The Figure 3a of the drawings is a detailed cross-section of a modi ied fo~m of the nozzle means sho~n in Figure ? in which the lower end of the nozzle means is tapered inwardly and showing a de~ailed cross-section of a modified transverse jet entraining means having a fla~ened orifice opening.
The Figure 3b of the drawings is a top plane view of the modified transverse jet entraining means and the nozzle means illustrated in Figure 3a of the drawings.
The Figure 3c of the drawings illustrates the use of the apparatus of Figure 3b to make fila-mented hollow glass microspheres.
DETAILED D I S CUS ~ IO~I
OF THE DRAt~l~GS

Referring to Figures 1 and 2 of the drawings, there is illustrated a vessel 1, made of suitable refractory ~aterial and ~eated by means not shown lS ror holding molten glass 2. The bottom floor 3 of vessel 1 con~ains a pl.urality of openings 4 throu~h ~vhich molten glass 2 is red to coaxial blowing nozzles S. The coaxial blowing nozzle S
can be made separatel~ or can be formed b~ a downwida extension of the. bo~tom 3 of vessel 1.
The coa~ial blowing nozzle S consises of an inner nozzle 6 having an orifice 6a for a gaseous material blowing gas and/or metal vapor and an outer nqæzle 7 having an orifice 7a for molten glass. The inner nozzle 6 is disposed wit~in and coaxial ~o outer nozzle 7 ~o orm annular space 8 between nozzles 6 and 7, which annular space provides a flow path for molten ~lass 2.
The orifice 6a of inner nozzle 6 terminates at or a short dis~ance above the plane or orifice _.

, ~ ~ 5~3~ 5 5 7a of outer nozzle 7.
The molten glass 2 at about a~mospheric pressure or at elevated pressure fl~s downwardly through annula~ s?ace 8 and fills the area between orifices 6a and 7a. The surface tension forces in molten glass 2 form a thin liquid mol~en glass rilm 9 across orifices 6a and 7a.
A gaseous material blowing gas lQ, and/o. a gas concaining a metal vapor, dispersed metal oarticles or an organo metal comoound which is at or below ambient temperature or which is heated by means not shown to about the temperature of the molten glass and which is at a pressure above the molten glass oressure at the blowing nozzle, is fed through distribution conduit 11 and inner coaxial nozzle 6 and brought into contact with the inner surface of molten glass film 9. The gaseous material blowing gas e~Prts a positive pressure on the molten glass film to blow and distend the film outwardly to for~ an elongated cylinder shaped liquid film 12 of molten glass ~illed with the inert blowing gas and/or metal vapor 10. The elongated cylinder 12 is closed a~ its outer end and is ccnnected at its inner end to outer nozzle 7 at the oeripheral edge of ori~ice 7a. A balancing ~ressure of an inert ~as, i.e. a slightly lower pressure, is pro-vided in tne area of the blowing nozzle into which the elongated cylinder shaped liquid film is blown.
The illus~rated coa~ial noz~le, Figure 2, can be used to produce microspheres having diameters three to five times the size of the inside diameter of orifice 7a and is us2ful .

~ 5 in blcwing low viscosity glass materials, i.e.
glass compositions at low viscosities.
A transverse jet 13 is used to direct an ; inert entraining fluid 14, which is heated to about, below or above the temperature of the molten glass 2, by means not shown. The .entraining 1uid 14 is fed through distribution conduit 15, nozzle 13 and transverse jet nozzle j orifice 13a and directed at the coa~ial blowing nozzle 5. The transverse jet 13 is aligned to direc~ ~'ne flow of ent~aining rluid 14 o~er and around blowing nozzle 7 in the microsphere rorming region at and behind the orifice 7a. The entraining fluid 14 as it passes over and around blowin~ nozzle 5 fluid dynamically induces a pulsating or fluctuating pressure field in the entraining fluid 14 at the opposite or lee side of blowing nozzle 5 in its wake or shadow.
The entraining fluid 14 envelops and acts on the elongated cylinder 12 in such a manner as to cause the cylinder to flap, fold, pinch and close-off at its inner end at a point 16 proximate to the ori~ice 7a of outer nozzle 7.
T~e continued movement or the entraining fluid 14 over .he elongated cylinder 1 produces fluid drag forces on the cylinder 1~ and detaches it rrom the orifice 7a of the outer nozzle 7 to allow the cylinder to fall, i.e.
to be en~rai~ed and transported away frcm nozzle 7. The surface tension forces o the molten glass act on the entrained, ralling elongated cylinder 12 and cause the cvlinder to seek a minimum surface area and to form a s~herical shape hollow molten glass S~55 microsphere 17.
Quench nozzles 18 having oririces 18a are disposed below and on both sides of coaxial blowing nozzle 5 and direct cooling fluid 19 at and into contact with the molten glass microsphere 17 to rapidly cool and solidify the molten glass and for~ a hard, smooth hollow glass microsphere. The quench fluid 19 also serves to carry the hollow glass microsphere away from the coaxial blowing nozzle 5.
Where a ~etal vapor is used with the blowing gas, the quench fluid cools and condenses the metal vapor to deposit the metal vapor on the inner wall surface of the microsphere as a transparent o`r ~a reflective metal coating 20. Additional cooling time, ir necessary, can be provided by using a fluidized bed, liquid carrier or belt carrier system for the hollow glass microspheres to harden the micro-spheres wlth substantiallv little or no dis-tortion or eff~ct on the size or shape of the microspheres. The cooled and solidified hollow glass microspheres are collected by suitable means not shown.
The Figure 3a o~ the drawings illustrates a prererred embodiment or ~he invention in which the lower portion of the outer coaxia nozzle 7 is ~apered downwardly and inwardly a~ 21. This embodiment as in the previous embodiment comprises coa~ial blowing nozzle 5which consists of inner nozzle 6 wich orifice 6a and outer nozzle 7 with orifice 7a'. The Figure of the drawings also sh~ws elongated cylinder shaped liquid film 12 with a pinched portion 16.
The use of the tapered nozzle 21 construction was found to substantially assist in the formation of a thin molten glass ~ilm 9' in the area between orifice ~a of inner nozzle 6 and orifice 7a' of outer nozzle 7. The inner wall surface 22 of the taper portion 21 of the outer nozzle 7 when pressure is applied to molten glass 2 forces the molten glass 2 to squeeze through a fine gap formed he-tween the outer edge of orlfice 6a, i.e. the outer edge of inner nozzle 6, and the inner surface 22 to form the thin molten glass film 9' across orifices 6a and 7a~. Thus, the formation of the molten film ~' does not in this embodiment rely solely on the sur-face tension properties of the molten glass.
The illustrated coaxial nozzle can be used to produce microspheres having diameters three to five times tha size of the diameter of orifice 7a of coaxial nozzle 7 and allows making micro-spheres of smaller diameter than those made using in Figure 2 apparatus and is particularly useful in blowing high viscosity glass materials.
The diameter of the microsphere is determined by the diam-eter of orifice 7a'. This apparatus allows the use of larger innerdiameters of outer nozzle 7 and larger inner diameters of inner nozzle 6, both of which reduce the possibility of pluggin~ of the coaxial nozzles when in use. These features are particularly advantageous when the blowing gas contains dispersed metal particles and/or the glass compositions contain additive material particles.

, `'~,. ~ 3i 5~~55i In Figures 3a and 3b of the drawings, the outer portion of the transverse jet 13 is flattened to form a generally rectangular or oval shaped orifice opening 13a. The orifice opening 13a can be disposed at an angle .elative to a line drawn through the central a~is o~
coaxial nozzle 5. The preferred anOle, however, is that as illustrated in the drawing. That is, ac an angle of about 90 to the cent~al axis of the coa~ial nozzle 5.
The use of the flattened transverse jet entraining fluid was found, at a given velocity, to concentrate ~he effect or the fluctuating pressure field and to inc~ease ~he amplitude of the pressure fluctuations induced in the region ot ~lle formation of the hollow microspheres a~
the opposite or lee side of the blowing nozzle 5.
By the use of the flattened transverse ~et and increasing the ampli~ude of the pressurc fluc-tuations, the pinching action exerted on thecylinder 12 is increased~ This action facili~
tates the closing Off Or the cylinder 12 a~
its inner pinc~ed end 16 and detaching of the cylinder 13 ~rom ~he ori~ice 7a or the cen~er nozzle 7.

The F.igure 3c of the drawings illustrates apparatus in~which a high viscosity glass material is used to blow hollow glass fila-men~ed microspheres. In this Figure, the elon~ated shaped cylinder 12 and glass micro-spheres 17a, 17b and 17c are connected to each other bv thin glass filaments 17d. As can be -- lg --.

, seen in the drawing, as the microspheres 17a, 17b and 17c progress away from blowing nozzle 5 surface tension forces act on the elonOated cylinder 12 tO effect the gradual change of the elongated shaped cylinder 12 to the generally spherical shape 17a, more spherical shape 17b and finally the spherical shape microsphere 17c. The same surface tension forces cause a gradual reduction in the diameter of the connecting filaments 17d, as the distance between the microspheres and ~ilaments and the blowing nozzle 5 increases. The hollow glass microspheres 17a, 17~ and 17c that are obcained are connected by thin filament por-tions 17d that are substantially of equallength and that are continuous with theglass microsphere.
The operation oE the apparatus illustrated in Figures 3a, 3b and 3c is ocherwise

2~ essentially the same as t:hat discussed above with regard to Figures 1 and 2 of the drawings.
The apparatus confi~urations illustrated in the Fi~ures of the dra.wings can be used singlY or in various com~inations as the si~uation may require. ~he entire apparatus can be enclosed in a high pressure containmen~
vessel, not sho~n, which allows ~he process to be carried out at elevated pressures.

~ 20 -.

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INORGANIC FIL~I FOR~ G 2~'~TERIAL
: AND GL~SS COMPOSITIONS
,, _ - ~ ~ S~3~ 5 5 The inorganic rilm ~orming material and compositions and particularly the glass compo-sitions ~rom which the hollow glass microspheresof the present invention are made can be widely varied to obtain the desired physical charac-teristics for heating, blowing, forming, cooling and hardening the microspheres and the 10 desired strength, gas permeability and light transmissicn characteristics o~ the glass microspheres produced.
The constituents of the glass compositions can be selected ar.d blended to have high resistance to corrosive gaseous materials, high resistance to gaseous chemical agents, high resistance to alkali and weather, low susceptibility to diffusion OL gaseous materials into and out of the glass microspheres, to be free o~ trapped gas bubbles or dissolved gases in the walls of the microspheres which can form bubbles and to have surficien~ strength when cooled, hardened and solidified to, when the microsphere contains a gaseous material compressed under very high pressure, withstand ~he contained pressure. The molten glass composition ~orms hard microspheres wh'ch are capable or con~acting adjacent microspheres without significan~ wear or de~erioration at che poincs of contact and are resistant to deterioration ~ro~ e.xposure to moisture, heat and/or weathering.
The constituents of the glass compositions can var~ widely, depending on the intended end uses, and can include naturally occurring and synthetically produced glass materials.

~ (3~ ~ 5 The glass compositions preferably contain relatively large amounts oE silicon dioxide, alumina, lithium, zirconia, and lime and relatively small amounts of soda. Calcium can j be added to assis~ in melting the glass and boric oxide can be added to improve the weathering properties of the glass. The glass compositions are ~ormulated to have relatively high melting and rluid flow temperatures with a relatively na~row temperature difference bet~een the melting and fluid flow ~empera-tures. The glass compositions are formulated such that they have a high rate of viscosity increase with decreasing temperature so that the microsphere walls will solidify, harden and strengthen before the blowing gas within the sphere decreases in volume and pressure a su~icient amount to cause the microsphere to collapse. I~here it is desirous to maintain a high pressure in the contained vol~e of the microspheres, the per~eability to gases such as helium (ambient) requires a reduction of the ne~worl~ formers, such as silica, and ~he inclusion o~ network modifiers, such as alumina. Other means for decreasing the permeability oE the hollow glass microspheres to gases, for e~ample by the addition of plane-orientable laminal flow particles, a~e discussed be`low.

: ~. . - . , ' The glass compositlons suitable for use in the present invention can have the range of proportions of the constituen~s listed below in Col~mns .~, B and C, in percent by weight.

T~BLE 1 A B C
(Alumina) ~ithium) (Zirconia) SiO2 46-~4 58-85 40-48 ~123 10-22 0-25 6-1 Li2O - 8-25. -Zirconia - - 8-20 CaO 5-18 0-2 1-3 ~g~ 0-12 0-2 0-4 Na2O 0-1 0-1.0 0-2.5 BaO 0-2.0 0-2.0 0-2.0 ~2 0-2.0 0-2.0 0_?,0 ~O 0-0.7 0-0.7 ~.5-1.5 : The compositions of Colu~ns A and B do not . 20 contain zirconia whereas the compositions of Col~nn C are relatively high in zirconia content.
The Column A glass compositions can be used for con~aining under high pressure gases sucn as o~gen, hydrogen, nit~ogen, carbon 25~ monoxide, car~on dioxide, ammonia, acetylene, methane, and natural gas.

::: `
~ ' , :

_ . . . . - -' '.

:
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ass The Column B glass compositions can be used for containing under high pressure gases such as helium, hydrogen, deuterium, tri~ium, argon and neon. These glass compositions are, S however, particularly useful for containing inertial confinement fusion fuel target gases such as deuterium, tritium, and mixtures thereof inasmuch as the Column B glass ccmpositions are substantially resistant to diffusion of gases into and/or out of the glass microspheres and are or low average atomic number.
The Column C glass compositions can be used for containing under high pressure gases such as ~enon, radon, krypton, argon, deuterium lS and tritium~ These glass compositions are also particularl~ useful for the storage of atomic fuel waste gaseous products. The microspheres made rom the Column C glass compositions can be stored in concrete or geological storage ~acilities inasmuch as the compositions are resistant to attack by al~ali.
The use of glass com~positions containing a relati~ely high alumina content and a rela-tivel~J low soda content was found to produce a rapid hardening of the glass microspheres, which facilitated the production of the glass microspheres.
The Table 2 below shows in Column I a high alumina content glass composition of the present invention and in Column II a high soda content glass composition heretofore used to make glass microspheres.

The glass microspheres made from the Columns I and II glass composi~ion are made in accordance with the present invention by blowing the glass with nitrogen as the blowin~ gas.

I II
(Alumina) (Soda) SiO2 57.0 72,2 ~123 20.5 1.~
CaO 5.5 8.3 ~gO 12 3.3 Na~O 1.0 14.2 The Table 3 below compares the increase ir.
viscosity on cooling of the high alumina con~ent (I) and the hign soda content (II) glass compo-sitions of Table 2, Tem~erature ~iscosity-Poises 20High ~lumina Comp. 2700F.30 (I~ 1830F.lOxL05 1470~.lOx101 High Soda Comp. 2700F.100 (iI) 1830F.lOx103 1~70F.lOx105 .

The Table 3 shows that the high alumina con~ent glass has a substantially faster hardening rate than the hi~h soda content glass sucn that in the first 1300F. or chilling, the high alumina content ~lass had a viscosity or 10x105 times greater than that of the high soda con-tent glass.
For certain uses rela~ively low temperature melting glass compositions can be used. The low melting glass compositions can contain relatively large amounts of lead. Naturally occurring glass materials such as basaltic mineral co~po-sitions can also be used. The use of ~ese naturally occurring glass composicions can in l; some cases substantially reduce che cost o~ the raw materials used.
Suitable lead containing glass compositions and basaltic mineral composi.tions are iTI Table 4 TABL,E 4 D E
(I,ead) (Basalt) SiO2 3~-70 40-55 2S Pb 10-60 Fe23 ~ 2-16 FeO - 1-12 CaO 0-5 7-14 ~gO 0-3 4-12 ~a2O 0-9 2-4 H2O - 0.5-4 Ti2 0.~-4 .. . . , . . _ . .. . .
t~See G.L. Sheldon, Forming Fibres from Basalt Rock, Platinu~ ~etals Review, pages 18 to 34, 1978.

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. . ..,, . ---- - -- -The discussions in the present applica~ion with respect to glass compositions is applicable to the various glass compositions mentioned including the naturally occurring basaltic mineral compositions.
To assist in the blowing and formation of the glass microspheres and to control the surface tension and viscosity of the s~neres suitable surface active agents, such as colloidal particles o~ insoluble substances and viscosity stabilizers can be added to che glass compo-sitions as additives. These additives can affect the viscosity o~ the sur.ace film of the micro-sphere to stabilize the film during the micro-sphere formation.
A distinct and advantageous ~eature of thepresent invention is that latent solid or latent liquid blowing gases are not used or required and that ~he microspheres that are produced are free o latenc solid or latent liquid blowing gas materials or gases.
The glass compositions from which the hollow glass microspheres can be made are, dependin~ on the particular glass materi.als used, to some degree permeable to the gas materials used to blow the microspheres and/or to t~e gases present in the medium surrounding the microspheres. The gas permeability of the gl2ss compositions can be controlled, modified and/or reduced or substantially s eliminated by the addition, prior to blowing the microspheres, to the glass composition of very small inert laminal plane-orientable additive material particles. Suitable S additive particles are copper, gold and aluminum leaf powders. When any one or more of these laminal plane-orientable additive material particles are added to a glass compo-sition prior to the blowing and formation of the hollow glass microsphere, the process of making the microsphere aligns the laminal particles, as the glass film is stretched in passing, i.e. extruded, through the conical blowing nozzle, with the walls of the hollow glass microsphere and normal to the gas difusion direction. The presence of the laminal plane particles in the microsphere walls substantially diminishes the gas permeability of the glass film. The sizes of the additive particles are advantageously selected to be less than one-half the thick-ness of the wall of the microspheres.
BLOWING GASES
The hollow microspheres, particularl~ the hollow glass microspheres can be blown with the desired blowing gas or with a gas containing a metal vapor, dispersed metal particles or an organo metal compound or mixtures thereof.
The desired gaseous material blowing gases are those for which ease in handling and storage are sought.

q~5S
The process and apparatus described above can be used to compress a wide variety o~ gaseous materials in hollow glass microspheres ~.~hich greatly facilitate the handling, processing, use, storage and dis-posal of the gaseous materials.

Examples of such gaseous materials are reusable gases such as oxygen, hydrogen, nitrogen, carbon monoxide, carbon dio~ide, air, helium, ammonia, neon, and acetylene.
The gases can readily be released from the microspheres merely by feeding the micro-sphere in an enclosed container be~ween twocounter rotating small steel drums. Where the contained gas is used as a ~uel, the microspheres can be ~ed directly into the combustion region. The surface of the drums can be slightly roughened so as to grasp and crush the microspheres ancl release the con-tained pressurized gases.
The microspheres can also be used to uniformlv mix t~.~o chemical reactant gases, separatel~f contained in m:icros~heres, or a chemically reactant g2S and a liquid prior to initiacing che chemical reaction.

The hollow glass microspheres may contain under pressure poisonous, toxic,

3~ corroslve and radioactive waste gaseous materials. Because the gaseous materials can be compressed under high pressure in the contained volume of the microspheres, - 2~ -a~s~ss relatively large volumes of ~he gaseous materials can be contained in relatively small microspheres.
The present invention avoids the use and need for heavy metal containers, complex valving systems and corrosion resistant alloys. The present invention finds particular and advan-tageous use in the handling and storage of poisonous gaseous materials such as hydrogen, cyanide, chlorine, bromine, and carbon monoxide gases and of radioactive waste gaseous materials such as radon, tritium, krypton and xenon.
The use o~ the microspheres to contain the gaseous materials renders the toxic, corrosive and radioactive waste gaseous materials relatively safe and easy to handle. These materials can be safely stored, as appropriate, in steel or lead containers, geological formations or mixed with and stored in concre~,e.
The hollow ~lass microspheres may contain under pressure gaseous laser ~uel materials such as tritium, deuterium, and mixtures thereof. The invention has particular utilicy in the manufacture of inertial confinement fuel targets for hydrogen fusion research and reactors.

.

3~ 5 5 The metal vapor when used in combination with the blowing ~as can deposit a metal coating on the inner wall surface of the hollow glass microsphere. The thickness of and nature of the metal coating deposited will determine whether the metal coatin~
is transparent or reflective of visible light.
The metal vapor when used with the blowing gas to blow the hollow glass micro-spheres is selected to have the desired vaporization cemperature, latent heat capaci~y and vapor pressure at the blowing temperature, and to have the desired vapor pressure at the solidification temperature and ambient tem-perature. The condensing and depositing of the metal vapor within the hollow glass microsphere ?roduces a vapor pressure af the metal vapor equivalent to the vapor pressure of the metal at room temperature, i.e. abou~ zero vapor pressure. The overall pressure contained within the microsphere will be that o the blowing gas (after cooling), e.g. lO0 to 1000 p.s.i.g. The thickness of the deposited metal coating will de?end ~o some e~tent upon ~he metal vapor partial pressure in the gas used ~o blow ~he microsphere, the si~é or the micro-sphere and the temperature of the molten glass.
The metal vapors of metals such as zinc, antimony, barium, cadmium, bismuth, selenium, li~hium, magnesium, and potassium can be used. Zinc and selenium, however, are preferred.

~ 5 5 A blowing gas containing dispersed metal ?articles can be used to obtain in the contained volume of the microsphere a deposit of a thir. metal coating on the inner wall surface of the hollow glass microsphere. The metal used to coat the inner wall surface of the hollow glass microspheres is selected to have the desired cr.aracteristics, and to adhere to the inner wall surface of the glass microspheres. The thickness or. the deposited metal coacing will depend to some e.~ten~ upon the met~l, the par~icle size of the metal used, the size of the microspheres and the amount of dispersed metal particles used.

}

~ `3~ S 5 The dispersed metal particle size can be 25A to lO,OOOA, preferably 50A to 5,000A and O O
more preferably lOOA to 1, OOOA. A sufficient amount of the metal is dispersed -in the blowing gas to obtain the desired thickness of the deposited metal. The dispersed metal particles can advantageously be provided with an electro-static charge tO assist in deposi~ing ~hem on - the inner wall surface of the microspheres.
~letal particles such as aluminum, silver, nic~el, zinc, antimony, bariu~, cadmium, cesium, bismuth, selenium, lithium, magnesium, potassium, and gold can be used. Aluminum, zinc and nickel, however, are preferred.
~ispersed metal oxide particles can in a similar manner be used to obtain si~ilar effects to that of the metals.
The thin metal coating can also be deposited on the inner ~all surrace of the microsphere by using as or with blowing gas organo me.al compounds th,at are gases at the blowing temperatures. ~f the organo metal compounds available, the organo car~onyl compounds are ?reerred. Suitable organo ~5 metal ca-bonyl compounds are nickel and iron.
The organo metal compounds can be decomposed by heating just prior to blowing the microspheres ~.o ob~ain finely dispersed metal particles and a decG~position product, e.g. a gas.
The decomposition gas, if present, can be used to assist in blowing ~he microspheres.
The dispersed metal particles from decompo-sition or the organo metal compound, as before, deposit to form the thin metal 3~ layer. .~lternatively, the microsphere, r after being ~ormed and containing the gaseous organo metal compound blowing gas, can be subjec~ed to an "elec~ric discharge" means which decomposes the organo metal compound to fo~m the finely dispersed me~al par~icles and the decomposition product.
The thickness of the deposited metal layer will depend prlmarily on the par~ial press~re of the gasecus organo metal blowing gas and the inside diame~er of the micro-sphere.
In each of the above discussed embodimen~s, the specific me~al ~sed 2S well as the thickness and nature of metal coating deposited will determine ~hether the metal coating is transparent or reflective of visible light.
Blowing gases can also be selec~ed that react r.~ith the inorganic ~ilm forming material or composition, e.g. the glass microspheres, for e~ample, to assist in the hardening of the microspheres or to make the microsphere less per~eable to the contained blowing gases.
The blowing gases can also be selected to react with the deposited ~hin metal layer.
A second blowing gas can advantageously be used in combination with the principle blowing gas to assist in the control of the cooling and`solidification of the hollow molten glass mlcrosphere, to react with the principle gas and/or to stabilize or initiate chemical degradation to a less to~ic or less poi.sonous ror~ such that the gaseous materials by passage of time become 5 ~
less hazardous. The auxiliary blowing gas can assist in the control of the cooling and solidification of the microspheres by maintaining the partial pressure of the auxiliary blowing gas in the microsphere for a sufficient period o time to allow the molten glass microsphere to solidify, harden and strengthen while the microsphere is cooled and hardened.
The entraining fluid can be a gas at a high or low temperature and can be selected to react with or be inert to the glass compo-sition. The entraining fluid, e.g. an inert entraining fluid, can be a high temperature gas. Suitable entraining fluids are nitrogen, air, steam, argon and xenon.
The gas in the area surroun~ing the blowing nozzle can be any suitable inert gas such as those that can be used as the entraining fluid, e.g. nitrogen, air, argon, and xenon.
An important feature of the present invention is the use of the transverse jet to direct the inert entraining fluid over and around the coaxial blowing nozzle. The entraining fluid assists in the formation and detaching of ~he hollow molten glass miero-sphere Crom the coaxial blowing nozzle.

The quench fluid can be a liquid, a liquid dispersion or a gas. Suitable quench fluids are ethylene glycol vapor or liquid, steam, a fine water spray, air, nitrogen or mixtures thereof. The hollow molten glass microspheres immediately after they are formed are rapidly quenched and cooled to solidify, harden and strengthen the glass microspheres before the internal gas pressure is reduced to such a low value that the microsphere coilapses.
The selection of a speciric quench fluid and quench temperature depends to some extent on the glass composition ~rom which the microsphere was formed and on the blowing gas or metal vapor used to blo~
the microsphere and on the metal and nature or the deposited mecal ~ilm desired.
PROCESS ONDITIONS
The inorganic film forming materials and/or composi-tions from which the microspheres are formed are inliquid form at the desired blowing temperature and during the blo~ing operation. The inorganic film forming materials and/or compositions are heated to a temperature of about 1800 to 3100F. and maintained in a liquid, fluid rorm during ~he blowing operation. The glass compositions are ~eated to a ~emperature of 20Q0 to 280bF., preferably 2300 to 2750F.
; and more prererablv 2400 to 2700F., depending on the constituen~s of the composition. The lead containing glass compositions can be neated to a tempera~ure of, for example, about 1~00 to 2900 F~ The basaltic mineral glass composi~ions can be heated to a tem-perature of, for example, about 2100 ~o ._r 3C~553100F, The glass compositions ac these tempera-~ures, i.e. the blowing temperatures, is ~olten, fluid and flows easily. The molten glass just prior to the blowing operation has a viscosity of lO to 600 poises, prererably 20 to 350 and more preferablY 30 to 200 poises. The molcen lead containing glass compositions just prior to the blowing operation have a viscosity or, for example, 10 to 500 poises.
The molten basaltic mineral glass composition just prior to the blowing operation can have a viscosity of, ror example, 15 tO 400 poises.
~ere the ?rocess is used to make non-filamented lS microspheres, the liquid glass just prior to the blowing operation can have a viscosity of 10 to 200 poises, preferably ?0 to 100 poises, and more preferably 25 ~o 75 poises.
I~here the process is used to make fila-mented microspheres, the liquid glass justprior to the blowing operation can have a viscositv of 50 to 600 poises, pre~erably 100 to 400 poises, and mor.e preferably 150 ~o 300 poises.
~S A critical feature of the process is that the formation of the hollow microspheres can be carried out at low viscosities relative to the viscosities heretorore used in the prior art processes ~0 that utili~ed latent.liquid or solid blowing agents dispersed throughout or contained in the glass compositions used to blcw the microspheres. Because or the abilicy to utilize comparatively low viscosities, applicanc is able to obtain hollow glass microspheres, the walls of which are free of any entrapped or dissolved gases or bubbles.
With the low viscosities used by applicant, any entrapped or dissolved gases di~fuse out and escape from the glass film surface during the bubble formation. With the high vis-cosities required to be used in the prior are processes, any dissolved gases or bubbles are trapped in the walls of the glass micro-spheres as they are formed because of the high viscosities required to be used.
The glass during the blowing operacion exhibits a surface tension of 150 to 400 dynes/cm, preferably 200 to 350 dynes/cm and ~ore ?referably 250 to 325 dynes/cm.
The molten glass fed to the coaxial blowing nozzle can be at ambient pressure or can be at an eleva~ed pressure. The molten or liquid glass feed can be at a pressure of l to 20,000 p.s.i.g., usuall~
3 to 10,~00 p.s.i.g. and rnore usually 5 to 5,000 p.s.i.g. Where the process is used to encapsulate gases a~ elevated pressures, the molten glass can be at: a pressure of 1 to 15,000 p.s.i.g., preferably lO0 to 6,000 p.s.i.g. and more prererably 500 to 3,000 p.s.i.g. The molten glass is continuously fed to the coaxial blowing nozzle durin~ the blowing operation to pre-ven~ premature breaking and detaching of the elongated cylinder shaped molten glass liquid film 2S i~ iS being formed by the blowing gas.

- 38 ~

~ 5 5 The blowing gas, gaseous material blowing gas and me~al vapor, dispersed ~etal particles or organo metal compound can be at about the same temperature as the molten glass being blo~n.
The gaseous material blowing gas tempera~ure can, however, be at a higher temperature than the molten glass to assist in maintaining the fluidity of ~he hollow molten glass micro--sphere during the blowing operation or can be at a lower temperature than the molten glass to assis. in the solidi~ication and hardening of the hollow molten glass micro-sphere as it iS formed.
The pressure of ~he gaseous material lS blowing gas or gaseous material blowing gas including metal vapor, dispersed metal particles or organo metal compounds is suf~icient to blow the m:icrosphere and will be slightly above the pressure of molten glass at the orifice 7a o the outer nozzle 7.
The gaseous material blowing gas can be a~ a pressure of 1 ~o ~0,000 p.s.i.g., usually 3 to 10,000 p.s.i.g. and more usually S to 5,000 p.s.i.g. The gaseous material when used to encapsulate gases at elevated pressures can also be at a pressure of 1 to 15,000 p.s.i.g., preferably 100 to 6,000 p.s.i.g.
and more preferably 500 to 3,000 p.s.i.g.
Depending on the particular gaseous material blowing gas used, the blowing gas or gaseous material blowing gas can be at a pressure of 50 to 20,000 p.s.i.g., prererabl~J more than 100, e.g. 200 to lO,OOO p~s.i.g. and more preferably S00 to 5,000 p.s.i.g. The blowing gas -3S~
pressure will also depend on and be slightly above the ambient pressure external to the blowing nozzle.
The pressure of the gaseous material blowing gas is sufficient to blow the micro-sphere and will be slightly above the pres-sure of the liauid glass at the orifice 7a of the outer nozzle 7.
The temperature of the gaseous material blowin~ gas will o~ course also depend on what che macerial is and its chemical decomposi~ion temperature and will be below its decomposition temperature.
The blowing gas temperacure will also depend on the viscosity-temperature-shear relationship of the glass materials used to make the microspheres. The temperature is obviously not a problem with gaseous materials which are themselves one o~
the basic elements.

-. .

The metal vapor blowing gas temperature will be sl-fficient to vaporize the metal and will be a~ about the same temperature as the molten glass being blo~n. The me~al vapor blowing gas temperature can. however, be at a higher temperature than the molten glass to assist in maintaining the fluidity of the hollow molten glass microsphere during the blowing operation or can be at a lower tem- -perature than the molten glass to assist in the solidification and hardening or the hollow molten glass microsphere as it is formed.
The pressure of the metal vapor blowing gas is suff cient in combination with the principle blowing gas to blow the micro-sphere and will be slightly above the pres-sure of molten glass at the orifice 7a of the outer nozzle 7. The pressure of the combined mixture of the blowing gases will also depend on and be slightly above the ambient pressure e:cternal to the blowing nozzle.
The ambient pressu~e external to the blowing nozzle can be at about atmospheric pressure or can be at super-atmospheric pressure. I~ere it is desired to ha~e a ; relatively or high pressure of contained gas in the microsphere or to deposit a relatively thick coating o~ metal within a ~icrosphere, t~e ambient pressure external to the blowing nozzle is maintained at a super-atmospheric pressure. The ambient pressure externai to the blowing noæzle will be such that it sub-stantially balances (i.e. is about equal to), but is slightly less than the blowing gas pressure.
Thus, the ambient gas pressure external to the blowing ~ 3S 5 nozzle will be about but slightly less than 1 to 15,000 p.s.i.g., preferably 100 to 6,000 p.s.i.g. and more preferably 500 to 3,000 p.s.i.g. The ambient pressure can also be about but slightly less than 50 to 20,000 p.s.i.g., preferably 100, e.g. 200, to 10,000 p.s.i.g. and more pre~erably S00 to 5,0~ p.s.i.g.
The transverse jet inert entraining fluid ~hich is directed over and around the coa~ial blowing nozzle to assist in the for~ation and detaching of the hollow molten glass microsphere from the coaxial blowing nozzle can be at about the temperature of the molten glass being blown. The entraining fluid can, however, be at a higher temperature than the molcen glass to assist in maintaining the fluidity of the hollow molten glass microspnere during the blowing operation or can be at a lower temperature than the molten glass to assist in the stabilization of the forming film and the solidification and hardening of the hollo~ mol~en glass microsphere as it is formed.
~5 The transverse jet entraining fluid can have a linear velocity in the region o microsphere formation of 1 to 120 ft/sec, usually 5 to 80 ft/sec and more usually 10 to oO ft/sec.

1.~ 5~
Where the process if used to make non-filamented microspheres, the linear velocity of the transverse jet fluid in the region of microsphere formation can be 30 to 120 ft/sec, preferably 40 to lO0 ft/sec and more preferably 50 to 80 ft/sec.
Ilhere the process is used to make fila-mented microspheres, the linear velocity of the transverse jet fluid in the region of microsphere ror~ation can be 1 to 50 ft/sec, preferably S to 40 ft/sec and more preferably 10 to 30 ft/see.
Further, it is found (Figures 2.to 4) that pulsing che transverse jet entraining fluid at a rate of 2 to 1500 pulses/sec, preferably 50 to 1~00 pulses/sec and more preferably lO0 to 500 pulses/sec assists in controlling the diameter or the microsphe~es and the length of the filament portion of the ila-mented microspheres and detaching the micro-spheres from the coaxial blowing nozzle.
The distance between filamented micro-spheres depends to some extent on che vis-cosity of the glass and che linear velocity or the transverse je~ entraining fluid.

._ 3'~ 5 The quench fluid is at a ~emperature such that it rapidly cools the hollow molten glass microsphere to solidify, harden and strengthen the molten glass before the inner gas pressure or metal vapor pressure decreases to a value at which the glass microsphere would colla?se.
The quench fluid can be at a temperature of O tO 500F., preferably 40 to 200F. and more preferably 50 to 100F., depending to some exten~ on the glass composition.
The quench fluid very rapidly cools the outer molten glass surface of the microsphere with which it is in direct contact and more slowly cools the blowing gas or metal vapor enclosed within the microsphere because of the lower thermal conductivity o~ the gas or vapor. This cooling process allows sufficient time ~or the glass walls ~0 of the microspheres to st:reng~hen before t~e gas is cooled and/or ~he me~al vapor is cooled and the pressure w:ithin the glass mi~rosphere is substantia:lly reduced.
The time elapsed frorn commencemenc of the blowing of the glass microspheres to the coolin~ and hardening or ~he microspheres can be .0001 to 1.0 second, preferably .0010 to 0.50 second and more preferably 0.010 to 0.10 second.
The rilamented microsphere embodiment of the invention provides a ~.eans by which the microspheres ~ay be suspended and allowed to harden and strengthen without being brought into contact wi th any surface.

,~.,. _ The filamen~ed microspheres are simply drawn on a blanket or dru~ and are suspended between the biowing nozzle and the blanket or drurn for a suficient period of time for them to harden and strengthen.
APPA~TUS
Referring to ~igures 1 and 2 of the drawings, the reractory vessel 1 is constructed to main-tain the molten glass at the desired operating ~emperatures. The molten glass 2 is ed to coaxial blowing nozzle 5. The coa~ial blowing nozzle 5 consists of an inner nozzle 6 having an outside diameter of 0.32 to 0.010 inch, preferably 0.20 to 0.015 inch and ~ore preferably 0.10 to 0.020 inch and an outer nozzle 7 having an inside diameter of 0.420 to 0.020 inch, preferably 0.260 to 0.025 and more preferablv 0.130 to 0.030 inch. The inner nozzle 6 and outer no7zle 7 form annular space 8 which provides a flow path through which the molten glass 2 is extruded. The distance between the inner nozzle 6 and out:er nozzle 7 can be 0.050 to 0.004, preferably 0.030 to 0.005 and more preLer~bly O.Q15 to 0.008 inch.
The orifice 6a of inner nozzle k terminates a short distance above the plane of oriice 7a of outer nozzle 7. The oriice 6a can be spaced above orifice 7a at a distance of 0.001 to 0.125 inch, preferably 0.902 to 0.050 inch and more preferably 0.003 to 0.025 inch. The mol~en glass 2 flows downwardly through annular space 8 and fills the area between orifices 6a and 7a. The orifices 6a and 7a can ~ ~ .

be made from stainless steel, platinum alloys, or fused alumina.
The surface tension forces in the molten glass 2 form a thin liquid molten glass film 9 across orifices 6a and 7a which has about the same or a smaller thickness as the distance of orifice 6a is spaced above orifice 7a. The molten glass film 9 can be 25 to 3175 microns, preferably 50 to 1270 microns and more preferably 76 to 635 microns thick.
A gaseous material blowing gas is fed through inner coaxial nozzle 6 and brought into contact with the inner surface of molten glass film 9. The blowing gas and/or metal vapor exerts a positive pressure on the molten glass film to blow and distend the film outwardly and downwardly to form an elongated cylinder shaped liquid film 12 of molten glass filled with the blowing gas l~. The elongated cylinder 12 is closed at its outer end and is connected to outer nozzle 7 at the peripheral edge of orifice 7a.
The Figure 2 blowing nozzl~e can be used to blow molten glass at relatlvely low viscosities, for example, of 10 to 60 poises, and to blow hollow glass microspheres of relatively thick wallsize, for example, of 20 to 100 microns or more.
The transverse jet 13 is used to direct an inert entraining fluid 14 through nozzle 13 and transverse jet nozzle orifice 13a at the coaxial blowing nozzle S. The .

coaxial blowing nozzle 5 has an outer diameter of 0.52 to 0.030 inch, prererablv 0.36 to 0.035 inch and more preferablv 0.140 tO 0. 040 inch.
~he process was found to be very sensitive to the distance of the transverse jet 13 from the orifice 7a of outer nozzle 7, the angle at which the transverse jet was directed at coaxial blowing nozzle 5 and the point at which a line drawn through the center a~is of transverse jet 13 intersects with a line drawn through the center axis of coaxial nozzle 5. The trans-verse jet 13 is aligned to direct the flow of entraining fluid 14 over and around outer nozzle 7 in the microsphere forming region of the orifice 7a. The orifice 13a of trans-verse jee 13 is located a distance of 0.5 to 14 times, prererably 1 to 10 times and more preferably 1.5 to 8 t:imes and still more preferably 1.5 to 4 times the outside diameter of coaYial blowing nozzle S away from the point of intersect of a line drawn along the center a.Yis of transverse jet 13 and a line drawn a1ong t~e center aYis of coaxial blowing nozzle j. The center a~is of transverse jet 13 is aligned at an angle of 15 to 85, preferably 25 to /5 and more preferably 35 to 55 relative to the center a~Yis of the coaYial blowing nozzle 5. The orilice 13a can be circular : in shape and have an inside diameter of ` 0.32 to 0.010 inch, preferably 0.20 to 0.015 inch and more prererably 0.10 to 0.020 inch.

~ 3~ S 5 The line drawn through the center axis of transverse jet 13 intersects the line drawn through the center axis of coaxial blowing nozzle 5 at a point above the orifice 7a of S outer nozzle 7 which is.S to 4 times, pre-ferably 1.~ to 3.5 times and more preferably 2 eo 3 times the outside diameter of the coaxial blowing nozzle 5. The transverse jet entraining fluid acts on the elongated shaped cylinder 12 to flap and pinch it closed and to detach it form the orifice 7a of the outer nozzle 7 to allow the cylinder to fall free, i.e. be transported away from the outer nozzle 7 by the entraining `
fluid.
The transverse jet entraining fluid as it passes over and around the blowing nozzle fluid dynamically induces a periodic pul-sating or fluctuating pressure field at the opposite or lee side of the blowing nozzle in the wake or shadow of the coa~ial blowing nozzle. A similar periodic pul-sating or ~luctuating pressure field can be produced by a pulsating sonic pressure field directed at the coaxial blowing nozzle.
; T'ne entraining fluid assists in the formation and detaching of-the hollow glass micro-sph.ere from the coaxial blowing nozzle.
The use of the transverse jet and entraining fluid in ~he manner described also dis-courages wetting of the outer wall surface of the coa~ial blowing nozzle 5 by the molten glass being blown. The wetting of the outer wall can otherwise disrupt and interfer with blowing the microsphere.

..

.. , , ~ . .. .... .. . . .
, , ~

The quench nozzles 18 are disposed below and on both sides of coaxial blowing nozzle 5 a sufficient distance apar~ to allow che microspheres 17 to fall between the quench nozzles 18. The inside diameter of quench nozzle orifice 18a can be 0.1 to 0.75 inch, preferably 0.2 to 0.6 inch and more preferably 0.3 to 0.5 inch. The quench nozzles 18 direct cooling fluid 19 at and into contact with the molten glass microspheres 17 at a velocity of 2 to 14, preferably 3 to 10 and more preferably 4 to 8 ft/sec to rapidly cool and solidify the molten glass and form a hard, smooth hollow glass microsphere.

Referring to Figure 3a, it is fcund ~hat in blowing high viscosity molten glass co~positions, i.e. molten glass compositions at high viscosities, that it was advantageous to immediately prior to blowing the molten glass to provide by extrusion a very thin molten glass liquid film for blowinO into the elonga~ed cylinder shape liquid ~ilm 12. Thle thin molten glass li.quid film 9' is provided by having ~he lower portion o~ the outer coa~ial nozzle 7 tapered downwardly and inwardly at 21. The tapered portion 21 and inner wall surface~22 ~hereo can be at an angle of 15 to 75, preferably 30 to 60 and more prererably about 45 relative to the center axis of coaxial blowing nozzle 5.
The orifice 7a' can be 0.10 to 1.5 times, preferably 0.20 to 1.1 times and more . - 49 -3~ ~ 5 pre~erabl~ 0.25 to .8 times the inner diameter of orifice 6a of inner nozzle 6.
The thickness o~ the molten glass liquid film 9' can be varied by adjusting the distance of orifice 6a of inner nozzle 6 above orifice 7a of outer no7zle 7 such that the distance between the peripheral edge of orifice 6a and the inner wall sur.ace 22 of tapered nozzle 21 can be varied. By controlling the distance between the peripheral edge of orifice 6a and ~he inner wall surface 22 of the tapered nozzle to form a very fine gap and by controlling the pressure applied ~o feed che ~olten glass 2 through annular space 8 the ~olten glass 2 can be squeezed and e~truded through the very fine gap to form a relatively thin molten glass liq~id film 9'.
The proper ga? can best be determined ~y pressing the inner coaxial nozzle 6 downward with sur~icient pressure to complecely block-of the flow of glass, and co then very slowly raise the inner coaxial nozzle 6 until a scable system is obtained, i.e.
until the microspheres are being formed.
The ~apered nozzle construction illustrated in Figure 3a can be used to blow glass compositions at relatively high viscosities as well as to blow glass compositions at the relatively low viscosities referred to with regard to Figure 2 of the drawings. The ~igure 3a construction is of particular advantage in blowing the thin walled microspheres.
~ hen blowing high viscosity glass compo-sitions, it was ~ound to be advantageous to obtain the very thin molten glass fluid film and ~o continue during the blcwing operation to supply molten glass to the elongated cylinder shapea liquid film as i~ was formed.
r~here a high pressure is used to squeeze, i.e. extrude, the molten glass through the very thin gap, the pressure of the blcwing g~
and/or blowing gas and ~etal va~or is generall-~ less than the molten glass feed pressure, but slightly above the pressure of the molten glass at the coa~ial blowing nozzle.
The tapered nozzle configuration of Figure 3a is also particularly useful in aligning the laminal plane-orientable glass additive materials. The passage o~ the glass material through the fine or narrow gap serves to align the additive ~aterials with the walls o~ the microspheres as the microspheres are being formed.
The Figures 3a and 3b o~ the drawings also illustrate preferred configurations in which the transverse jet 13 is flattened to form a generally rectangular or oval shape. The orifice 13a can also be flattened to form a generally oval or rectangular shape. The width o the orifice can be 0.96 to 0.030 inch, preferably 0~0 to 0.045 inch and more preerably 0.30 to 0.060 inch. The height o~ the orifice can be 0.32 to 0.010 inch, preferably 0.~0 to 0.015 inch and more preferably 0.10 to 0.0~0 inch.

. .
The Fi~ure 3c of the drawings illustra~es a conEiguration in which a glass material or composition a~ high viscosity is used to blow filamented hollow glass microspheres. The drawing shows the formation of the uniform diame~er micro-spheres space~ about equal distances apart.
The numbered items in this àrawing have ~he same meanings as discussed above with reference to Figures 1, 2, 3a and 3b.
DESCRIPTION OF THE ~IICROSPHER~S
.. ..
The hollow microspheres made in accordance with the present invention can be made from a wide variety of inorganic film forming materials and compositions, ~articularly glass compositions.
The hollow microspheres made in accordance with the present invention can be made from suitable inorganic film forming composi~ions.
The compositions are preferably resistant to high temperatures and chemical at~ack, resistant to corrosi~e and alkali and resistant to weathering as the situation may require, The inorganic film forming compositions that can be used are those that have the necessary viscosi~ies, as mentioned above, when being blown to ~orm stable films and which have a rapid change from the molten or liquid state to the solid or hard state with a relatively narrow temperature change.
That is, thev change from liquid to solid within a relatively narrowly defined tempera-ture range.

.

~ 3~ ~ 5 . ~
The hollow glass microspheres made in accordance with the present invention are preerably made from glass compositions.
The glass microspheres are substantially uniform in diameter and wall thickness, and have a clear, hard, smooth surface. The walls o~ the microspheres are free of any holes and substantially free of any relativel~
thinned wall portions or sections, sealing tips, trappea gas bubbles or sufficient amounts of dissolved gases to form bubbles.
The microspheres are also rree of any latent solid or liquid blowing gas materials or gases. The preferred glass compositions are those that are resistant to al~ali, chemical attack, high temperatures, ~eathering and diffusion of gases into and/or out of the microspheres. Where the gases to be encapsulated may decompose at elevated temperatures, glass compo-sitions that are molten below ~he decompo-sition temperatures of the gases can be used.
The microspheres after being formed can be reheated to soften the glass and enlarge the microspheres and/or to improve the sur~ace smoothness of the microspheres.
On reheating, the internal gas pressure will increase and cause the microsphere to increase in size. After reheating to the desired size, for example, in a "shot tower", the microspheres are rapidly cooled to retain the increase in size.

;t~5i5 The glass microspheres can be made in various diameters and wall thickness, dependlng upon the desired end use of the micro-spheres. The microspheres can have an outer diameter of 200 to 10,000 microns, preferably 500 to 6,000 microns, e.g, 500 to 2,000 microns, and more preferably 1,000 to 4,000 microns. The micro-spheres can have a wall thickness of 0.1 to 1,000 microns, prefer-ably 0.5 to 400 microns, e.g. 10 to 100 microns, and more prefer-ably 1 to 100 microns. Where a particular use or need requires it, the microspheres can also be made to have a wall thickness o~ 10 to 1,000 microns, preferably 20 to 400 microns and more preferably 50 to 100 microns.
The microspheres, because the walls are free of any holes and substantially free of any thinned wall sections, trapped gas bubbles, ancl/or sufficient amounts of dissolved gases to form trap-ped bubbles, are substantially stronger than those heretofore pro-duced. The absence of a sealing tip also makes the microspheres stronger.
The high pressure gas containing microspheres a~ter cooling to ambient temperatures can contain a gaseous material at about ambient pressure or at superatmospheric pressure in the enclosed volume. The microspheres can have a contained gas pressure of about 5 to 8,000 p.s.i.g., usually 15 to 1,600 or 2,000 p.s.i.g. and more usually 90 to 1,000 p.s.i.g. The contained gaseous materials can also be at pressures of l to 2,000 p.s.i.g., and 100 to 1800 p.s.i.g.
The contained gas pressures are preferably at 800 to 1200 p.s.i.g., depending on the contained gaseous materials. Depending on the glass composition, diameter and wall thickness of the microspheres, the micro-spheres can contain gases under pressures of up to and/or greater than 3,00C to 5,000 p.s.i.g.
The microspheres can contain a metal coating on the inner wall surface of the hollow microspheres when a metal vapor, dispersed metal paxticles and/or an organo metal compound is mixed with the gaseous material blowing gas.
The thickness of the metal vapor coating deposited on the inner wall sur~ace of the microsphere will depend on the metal vapor used to blow the micro-sphere, the pressure of t:he metal vapor and the size o~ the microsphere. The thickness o~ the ~etal coating can be 25 to lO,000~, prererablv 50 to S,OOOA and more preferably 100 to l,000~. The thickness o the metal coating can also be 25 to 1, OOOA, preferably 50 to 600A and more preferably 100 to 400A.
The microspheres can also contain a thin metal layer deposited on the inner wall surface of the microsphere where the blowing gas CQntainS dispersed metal particles or an ~ organo metal compound. The thickness of the ; thin metal coating deposited on the inner wall ... . ~ , :

` ~ ' ;5 sur~ace of the microsphere will depend on the amount and particle size o~ the dispersed metal particles or partial pressure of organo metal blowing gas tha~ are used and the diameter o~ the microsphere. The thickness of the thin metal coating can be 25 to lO,OOOA, preferably 50 to 5,000A and more preferably 100 to l,OOOA.
~lhen it is desired that the deposited metal coating be transparent, the coating can ~e less than lOOA and preferably less than SOA. The transparent metal coated microspheres can have a deposited metal coating 25 to 95A and preferably 50 to 80A thick. The microspheres, though transparent to visible light, are sub-stantially reflective of in~rared radiation.
I~hen it is desired that the ~eposited metal coating be reflective, the coating can be more than 100A and preferably more than 150A thick. The ref:Lective metal coated microspheres can have a deposited metal coating 105 to 600A and pre~erably 150 to 400A thick and more preferably 150 to 250A thick.
The microspheres can be fonmed in . ~
a manner such that they are connected by continuous thin glass filaments, that is they are made in the rorm of filamented microspheres. The length of the connecting filaments can be 1 to 40, usually 2 to 20 and more usuallv 3 to 15 times the diame~er of the microspheres. The diameter, that ; 35 is the thickness o~ the connecting filaments, can be 1/5000 to 1/10, usually 1/25C0 to 1/~0 and more usually 1/1000 ~o 1/30 of ~he diameter of the microspheres.
In an embodiment of the invention, the S ratio of the diameter to the wall thickness of the microspheres is selected such that the microspheres are flexible, i.e. can be deformed under pressure without breaking.
The diameter and wall thickness of the hollow microspheres ~ill o~ course effect the average bulk density of the microspheres. The glass microspheres pre-pared in accordance with the invention will have an average bulk density of 0.2 tO 15 lb/ft3, preferably O.S to 10 lb/ft3 and more preferably 0~75 to 6 lb/ft3. r.~ere increase strength is desired, the micro-spheres can have an average bulk density of 1.0 to lS lb/ft3, preferably 1.5 to 12 lb/ft3 and more preferably 2 to 9 lb/ft3.
The hollow glass microspheres of ~he present invention can be used to, for example, contain o~ygen gas (at ambient temperature) under a pressure oE 100 ~o 3,000 p.s.i.g., pre~erably 100 to 1,000 p.s.i.g. and hydrogen under a pressure or 50 to 4,000 p.s.i.g., preferably 50 to 2,000 p.s.~.g.
(a~ ambien~ pressures). The respective gases -can be placed in relatively light weight 3~ containers and used for under water oxygen torch cutting or welding. The oxygen con-tainer and hydrogen container can each contain a small "roller drum" mill to which is fed necessary amounts or the respective microspheres ~o obtain and maintain a desired operating pressure ~or each of the gases. The oxygen con~aining .

5~
glass microspheres can also be used in sub-mersible vessels for emergency oxygen supply.
This procedure avoids the need of heavy pres-sure resistant metal cylinders and complex valve and metering systems.
Microspheres containing oxygen under high pressure can be stored separately than mixed or can be directly mixed with a solid, powdered or liquid fuel such as used in rocket engines.
The solid or liquid fuel and/or oxvgen con-taining microspheres are fed directly into a combustion chamber, the oxygen released and anv remaining portion or the microspheres expelled with the combustion e~haust pro-ducts.
The mic~ospheres can also be used todesign low pollution exhal~st combustion engines.
The o~vgen containing microspheres can be used with methane or hydrogen con~aining ; 20 microspheres. The respective microspheres would be crushed to release the contained gases, the gases mixed and burned to drive a turbine or "conventional" internal com bustion engine Any unburned remains of the crushed microspkeres are collecced and later removed fro~ the engine.

he hollow glass microspheres are made which contain a mixture of deuterium and tritium gases at a pressure of 1000 to 1500 p.s.i.g. (ambient temperature) which find particular use as targets in laser hydrogen fusion reactors and/or research. These microspheres can be stored at about ambient .

~s~s~

temperatures ~ithout any significant diffusion of the high pressure gases out of the microspheres.
The hollow glass microspheres may contain carbon monoxide gas at pressures of 500 to 3000 p.s.i.g., preferably 500 to 1000 p.s.i.g. (ambient temperature) which greatly facilitates the handling and/or storage of this gas.
The hollow glass microspheres may contain an unstable gas, for example, acetylene at pressures of 10 to 750 p.s.i.g.
(ambient temperature). The use of microspheres to contain the acetylene gas is found to stabilize the gas by limiting the contact between adjacent gas molecules such that chain decomposi-tion reactions of the gas molecules do not occur.
Radioactive fuel waste gases such as xenon and iodine may be encapsulated in the hollow glass microspheres at contained gas pressure o~ 400 to 600 p.s.i.g. (ambient temperature). These microspheres can be stored in geological formations or mixed with concrete, surrounded by a lead shield and safely stored in any suitable location.
The microspheres may contain oxygen under high pressure and can be uniformly mixed with solid, plastic, liquid or gaseous explosive materials to make a stable premixed explosive -lr,~ 55 composition with a self contained oxident.
Since the oxvgen is contained in the micro-sphere, it is completely separated from the explosive material and until time of detona-tion the e~plosive mixtures are very stable.
The mix~ure is detonated bv a conventional percussion cap. The present invention thus avoids the need of nonstable and e~pensive oxidents.
The simplicity, controllability and low cost of the microsphere system of the present invention allows for the storage, shipment and uses of gases under high pressure wit~ the same ease of handling as liquids and/or free flowing powders. A particular advantage of the disclosed system would be in reacting tr~o or more gaseous materials or a reactant gas and a liquid. For ex~mple, the reactant gases could be first homogeneously mi~ed and the reaction carried out by ~eeding the mi~ture to a reaction vessel in which the mi~ed microspheres would be crus~ed at a controlled rate.
The hollow glass microspheres are dry, inert, free ~lowing and can be safely handled and processed, and do not require special storage or handling ~acilities. Further, since the volume and pressure o eac~
microsphere is controlled, the weighc of a given amount of gas is easily measured.
The hollow glass microspheres o~ the present invention have a distinct advantage of being very strong and capable of supporting a substantial amount of weight.
~`

. . .

s They can thus be used to make simple inexpensive self-supporting or load bearing handling and storage systems.
A specific and advantageous use of the hollcw glass micros?heres of the invention is in manufacture of inertial confinement fuel target systems and systems for the storage of radioactive atomic waste materials.
EX~PLES
E~ample 1 A glass composition (Col. A) comprising the following constituents is used to make hollow glass microspheres.
2 A123 CaO ~gO B2o3 Na20 W~% 55-57 18-22 5-7 10-12 4-5 1-2 The glass composition is heated to a temperature of 2650 to 2750F. t.o form a fLuid molten gl~s ~avmg a viscosity of 10 to 60 poises, e.g. 35 to 60 poises and a surface tens:ion of 275 to 325 dynes per cm.
The molten glass is i.ed to the apparacus of Figures 1 and 2 of the drawings. The molcen glass passes through annular space 8 of blowing nozzle 5 and forms a thin liquid molten glass film across the orifices 6a and 7a. The blowing nozzle 5 has an outside diamèter of 0.040 inch and orifice 7a has an insi~e diameter of 0.030 inch.
The thin liquid molcen glass film has a diamecer or 0.030 inch and a thickness of O.005 inch. An oxygen gaseous material blowing gas at a temperature or 2650F. and 3~55 at a pressure of 6000 to 3000 p.s.i.g. is applied to the inner surface of the molten glass film causing the film to distend down wardly into an elongated cylinder shape with its outer end closed and its inner end attached to the outer edge of orifice 7a.
- The pressure in the area of the blowing nozzle is maintained at slightly less ~han 6000 to 8000 p.s.i.g.
The transverse jet is used to di~ect an inert entraining fluid which consists of nitrogen at a temperature of ~600F. over and around the blowing nozzle 5 which entraining fluid assists in the ~or~ation and closing of the elongated cylinder shape and the detaching of the cylinder from the blowing nozzle and causing che cylinder to fall free of the blowing nozzle. The trans-verse jet is aligned at an angle of 35 to ~0 50 relative ~o the blowing nozzle and a line dra~n through the center axis of ~he transverse jet intersects a line drawn through the center a~is of the blowing nozzle 5 at a point ~ to 3 ~imes the ou~-side diameter of the coa~ial blowingno~le 5 above the orifice 7a.
The free falling elongated cylinders filled wi~h o~ygen gas quickly assume a spherical sh`ape and are rapidly cooled to about ambient temperature by a quench fluid consisting of a fine water spray at a temperature of 90 to 150~. which quicklY cools, solidifies and hardens ~he glass microspheres.

.. . . . .. . .

5 ~
Clear, uniformed size, smooth hollow glass microspheres having a 20C0~o 3000 micron diameter, a 3 to 10 micron, preferably a 20 to 30 micron, wall thickness and filled with oxygen gas at an internal contained pressure of 1025 to 1370 p.s.i.g. are obtained.
The microspheres are closely e:~amined and the walls are found to be free of any trapped gas bubbles.
Exam~le 2 A glass composition (Col. B) comprising the following constituents is used to make transparent hollow glass microspheres.

2 123 Li2 MgO B2O3 Na2O K2O
~t% 6~-64 6-8 14-16 0-2 2-3 1-2 0.5-1 The glass composition is heated ~o a tempera~ure of 2650 to 2750F. to form a fluid molten glass having a viscositv of 35 to 60 poises and a surace tension of 275 to 325 dynes per cm.
The molten glass is ~ed to the apparatus of Figures 1 and 3a of the drawings. The molten ~lass is passed through annular space 8 of blowing nozzle 5 and into tapered portion 21 o outer nozzle 7~ The molten glass under pressure is squeezed through a fine gap formed between the outer edge of oririce 6a and the inner surface 22 of the tapered portion 21 of outer nozzle 7 and forms a thin liquid molten glass film across the orifices 6a and 7a'. The blowing nozzle S has an out-side diameter of 0.04 inch and orifice 7a' has an inside diameter of 0.01 inch. The thin liquid molten glass film has a diamecer of 0.01 inch and thickness of 0.003 inch.
A mixture of deuterium and tritium gases, for manufacture of inertial confinement system targets, is used as the blowing gas at a temperature of 2700F. and at a pres-sure o~ 1~,000 to 14,000 p.s.i.g. is applied to the inner surface of the molten glass film causing the ~ilm to distend outwardly into an elongated cylinder shape ~ith its outer end closed and its inner end attached to the outer edge of orifice :~ 7a'. The pressure in the area of the blowing nozzle is maintained at slightly less than 12,000 to 14,000 p.s.i.g.
The transverse jet is used to direct an inert entraining ~luid which consists of nitrogen at a temperature of 2600F.
over and around the blowing nozæle 5 ~hich entraining fluid assi.sts in the formation and closing of~ of the elongated : cylinder shape and the detaching of the cylinder ~rom the blowing nozzle and causing ~5 the cylinder to rall free of the blowing nozzle. The transverse jet is aligned at an angle of 35 to 50 relative to the blowing nozzle and a line drat~n through the cènter axis of the trans-verse jet intersects a line drawnthrough the center axis of the blo~ing nozzle 5 a~ a point 2 to 3 times the outside diameter of the coaxial blowing nozzle 5 above orifice 7a'.

. - 64 -The free falling elongated cylinders filled with the inertial confinement fuel gas quickly assume a spherical shape. The micro-spheres are contacted with a quench fluid S consisting of a fine water spray at a tem-perature of 90 to 150F. which quickly cools, solidifies and hardens the microspheres.
Clear, uniformed size, smooth, hollow glass microspheres having an about 800 to 900 micron diameter, a 8 tO 20 micron wall thickness and an internal contained pressure of laser target fuel of 2040 to 2380 p.s.i.g. The thin walls of the micro-spheres are free of any trapped gas bubbles.
Exam~
The glass composition (Col. C) comprising the ~ollowing constituents is used to make hollow glass microspheres.
SiO2 A12O3 Zirconla CaO MgO B203 Na2O K2O
Wt% 45-55 8-10 16-18 1-2 0-1 1-2 1-2 0-1 The glass composition is heated to a temperature of 2650 to 27S0F. to form a ; fluid molten glass having a viscosity of 35 to 60 poises and a surface tension of 275 to 325 dynes per cm.
The molten glass is fed to the apparatus of Figures l and 3a of the drawings. The molten giass is passed through annular space 8 of blowing nozzle S and into tapered portion 21 of outer nozzle 7. The molten ~lass under pressure is squeezed through a fine gap between the outer edge of orifice 6a and the inner surface 22 of ~ 5 S
,~, the tapered portion 21 of outer nozzle 7 and forms a thin liquid molten glass fil~ across the orifices 6a and 7a'. The blowing nozzle 5 has an outside diameter or O.OS inch and orifice 7a' has an inside diameter of 0.03 inch. The thin liquid molten glass film has a diameter of 0.03 inch and a thickness of 0.01 inch. A gaseous atomic energy fuel waste product consisting of tritium blowing gas at a temperature of 260QF.
and at a pressure of 5000 to 6000 p.s.i.g.
is applied to the inner surface of the molten glass film causing the film to distend out~ardlv into an elongated cylinder shape with its outer end closed and itS inner end attached to the outer edge of orifice 7a'. The pressure in the area of the blowing nozzle is maintained at slightly less than S000 to 60~0 p.s.i~g.
~ 20 The transverse jet is used to direct `; an inert encraining ~luid which consists o nitrogen gas at a temperature of 2500F.
over and around the blowing nozzle 5 which entraining Cluid assists in the formation ~5 and closing or the elongated cylinder shape and the detaching of ~he cylinder from the - blowing nozzle and causing the cylinder to fall free of the blowing nozzle. The transverse j`et is aligned at an angle of 35 to 50 relative to the blowing nozzle and a line drawn through the center axis of the transversè jet intersects a line drawn through the center a~is of the blowing nozzle 5 at a point 2 ~o 3 times 3~ 5 S
~;
the outside diameter of rhe coa~ial blowing nozzle 5 above orifice 7a'.
The rree falling elongated cylinders filled with the gaseous atomic waste material quickly assume a spherical shape. The microspheres are contac~ed with a quench fluid consisting of an ethylene glycol spray at a temperature of 0 to 15F. which quickly cools, solidifies and hardens the glass microspheres.
Clear, uniformed size, smooth, hollow glass microspheres having an about 3000 to 4000 micron diameter, a 10 to 20 micron wall thickness and an internal contained lS pressure or the atomic gas waste material of 850 to 102n p.s.i.g. are obtained. ~ne glass compo-sition from which these microspheres are made are alkali resistant: and the micro-spheres can ~e convenient:ly stored in concrete.
E~am~e 4 A hollow glass microsphere containlng hydrogen gas under pressure is made using the same glass composition, appara'us and ?rocedure described in E~zmple l with the following differences. Hydrogen gas is used as the gaseous material blowing gas a~ a temperature~o~ 2400F. and a pressure of 4000 co 5000 p. s . i. g. is applied to the inner surface of the molten glass film causing the film to distend downwardly into an elongated cylinder shape with its outer end closed and its inner end attached to the oucer edge of orifice 7a. The _ ~1 ~5I~55 pressure in the area of the blowing nozzle is main~ained ac slightlv less than 4000 to 5000 p.s.i.g.
The transverse jet as beore is used to direct an inerc en~raining fluid which con-sists of nitrogen at a temperature of 2400F.
over and around the blowing nozzle 5 which entraining fluid assists in the formation and closing of the elongated cylinder snape and the detaching of the cylinder from the blowlng nozzle and causing the cylinder to fall free of the blowing nozzle.
The free falling elongated cylinders filled with hydrogen gas quickly assume a spherical shape and are rapidly cooled as before to about ambient temperature by a quench fluid which quickly cools, solidiies and hardens the glass micr.ospheres.
Clear, uniformed size, s~ooth, hollow glass microspheres having a 2000 to 3000 micron diameter, a S to 10 micron wall thi~kness and filled with hydrogen gas at an internal concained plressure of about 750 to 950 p.s.i.g. are obtained. The hydrogen gas containing mic-ospheres can be used to store and handle hydrogen gas and can themselves be used as a fuel in an hydrogen-oxygen combustion svstem.

~ 5 Example 5 .
A hollow glass microsphere con~aining carbon dioxide gas under pressure is made using the same glass composition, apparatus and procedure described in Example l wi~h the follo~ing differences. Carbon dio~ide gas is used as the gaseous material blowing gas at a temperature o~ 2400F. and a pres-. sure of 4000 to S000 p.s.i.g. is applied to the inner surface of the molten glass filmcausin~ the film to distend outwardly into an elongaced cylinder shape with i~s outer end closed and its inner end attached to the outer edge of orifice 7a. The pressure in the area of the blowing nozzle is main-tained at slightly less than 4000 to S000 p.s.i.g.
The transverse jet as before is used to direct an inert entrai.ning fluid which consists or nitrogen a~ a temperature of 2400F. over and around the blowing nozzle 5 which entraining luid assists in the formation and closing o~ of the elongated cylinder shape and the detaching of the cylinder from the blowing noz71e and causing the cylinder to fall free of the blowin~ nozzle.
The free falling elongated cylinders filled with carbon dio~ide gas q~ic'~ly assume a spherical shape and are rapidly coole& as before to about ambient tem-perature by a quench fluid which quickly cools, solidifies and hardens the micro-spheres.

~ - 69 -, . . ...... . . . _ _ Clear, uniformed size, srnooth, hollow glass microspheres having a 2noo to 3000 micron diameter, a 5 to 10 micron wall thick-ness and filled with carbon dioxide gas at an internal pressure o about 750 to 950 p.s.l.g. are obtained. The carban dioxide con-taining microspheres can be used to store and handle carbon diaxide gas and can themselves be used in a "dry powder" fire extinguisher system as the fire extinguishing ingredient.
A transparent or reflective metal coating can be deposited on the inner wall surface of the microspheres produced in accordance with the above Examples by the addition to the blowing gas of a metal vapor, e.g. zinc vapor, dispersed metal particles~ e.g~
aluminum powder or an organo metal compound, e.g. nickel carbonyl.
The microspheres can also be made in a non-filamented as well as a filamented form by following the teachings of the presen~ invention.
Further, applicant in his copending application Serial No. 334,618 filed August 27, 1979 has presented specific Examples for making microspheres having a thin metal layer deposited on the inner wall surface thereof ~rom a blowing gas consisting a metal vapor and from a blowing gas containlng dispersed metal particles and ~or making non~filamented microspheres and filamented microspheres - UTILITY
The hollow glass microspheres of the present invention have many uses including the handling and storage of oxygen, hydrogen, nitrogen and carbon dioxide at high pressures in light easy to handle containers The process and apparatus described herein can also be used to encapsula~e and store gaseous materials in hollow glass micro-spheres of a suitable non-interacting composition, thereby allowing - 70 ~

ss handling or storage of gases generally, and of corrosive and toxic or otherwise hazardous gases specifically. Because of the relative great strength of the microspheres, the gases may be encapsulated ln the microspheres and stored at high contained gas pxessures. In the case where disposal by geological storage is desired, for example, for poisonous and/or other toxic gases, the gases can be encapsulated in very durable alumina silicate composition or æircon-ia composition glass microspheres which can subsequently be embed-ded, if desired, in a concrete structure. The glass microspheres of the present invention, because they can be made ~o contain gases under high pressure, can be used to manufactur~ fuel targets for inertial confinement fusion reactor systems.

S
The microspheres can be used to manu-acture inertial confinement fusion fuel targets for use in hydrogen fusing reactors and/or research. Because of the abilicy of manufacturing microspheres of specific diameters and wall thicknesses in which there is contained the target fuel under predetermined high pressure and because the microspheres can be produced with glass compositions ~hich substantially prevent diffusion of gases into or out of the microspheres and glass compositions which have the desired acomic constituents, the microspheres find particuLar and advantageous use in the manufacture of the inertial confinement targets.
The present invention also has particular utility for encapsulating toxic, corrosive and/or radioactive gaseous materials in a manner such thac chey can be compressed at a high pressure to a sub-stantially reduced volume and pu~ into a form concained in the mic:rospheres in which they are safe and easv co handle.
The constituents of the g:Lass composition can be selected to be resistant to attack bY che material encapsulated and can be made resistant to alkali such that the microspheres`can be mixed with and stored in concrete bloc~s. The concrete blocks can be safely shipped to geological sites for permanent storage.

The process and apparatus described above can be used to blow microspheres from any suitable molten material having sufficient viscosity and surface tension a~ the temperature at which the microspheres are blo~n to form the elongated cylinder shape of the material being blown and to subsequently be detached to form the spherical shape microspheres.
~here the gases to be encapsulated are unstable at high temperatures, low tempera-ture melting glass compositions can be used such as those containing relatively high concentrations of lead and/or thallium.
The microspheres, because they are made from very stable glass compositions, are not subject to degradation by out-gassing, aging, moisture, weathering or biological at~ack and the glass from ~0 whic~ the microspheres are made do not produce toxic fumes when exposed to very high temperatures or fire.
The glass compositions can be trans-parent, translucent or opaque. A suitable coloring material can be added to the glass compositions to aid in identifi-cation o~ microspheres of speciried size, wall thickness and contained gaseous material. The coloring materials can also be used to identify the contained - gas pressures.
The glass compositions can also be selected to produce microspheres that will be selectively permeable to specific gases and/or organic molecules.

.

~.~5i~`4355 These microspheres can then be used as semi-permeable membranes to separate gaseous or liquid mixtures.
The process and apparatus can also be use~ to form microspheres from ther~osetting and thermo-plastic resin materials such as polyethylene, polypropylene, polystyrene, polyesters, polyurethanes, phenolformaldehyde resins and silicone and carbonate resins. The lower temperature melting resins are particularly useful for encapsulating gases that are unstable at high temperatures.
The process and apparatus can also be used to form microspheres from metals such as iron, steel, copper, zinc, tin, brass, lead, aluminum, and magnesium~ In order to form microspher~s from these materials, suitable additives are used which provide at the film surface of the microsphere a sufficiently high viscosity that a stable microsphere can be formed.
In carrying out the process, the molten material to be used ~o torm ~he microspheres is selected and can be ~rea~ed and/or mixed with other materials to adjust their viscosity and surface tension characteristics sucn that at the desired blowing temperatures they are capable of forming hollow mlcrospheres of the desired size and wall thickness.

3~;;5 ..... ~
The process can also be carried out in a centrifuge apparatus in which the coaxial blowing nozzles are dis-posed in the outer circumferal surface of the centriruge at an angle of 15 to 75 away from the direction of rota~ion. ~olten glass is fed into the centrifuge and because of centrifugal forces rapidly coats and wets the inner wall surface of the outer wall of the centrifuge. The molten glass is fed into the outer coaxial nozzle. The inlet ~o the inner coa~ial nozzle is disposed above the coating of molten glass. The blowing gas is as before fed into the lS inner coaxial nozzle. The transverse jet entraining fluid is provided by the action of the ambient gas outside or the cencrifuge as che centri~uge rotates about its central axis. ~n e~ternal gas can be directed along the longitudinal a.Yis of the centrifuge. to assist in removing the microspheres from the vicini~y of the centri~uge as they are ~ormed. Quench fluid can be provided as before~
These and other uses of the present invention.will become apparent to those skilled in the art rrom the foregoing description and the following appended claims.
It ~ill be understood that various changes and modifications may be made in the invention and that the scope thereof is no~ to be limited except as set ~orth in the claims.

Claims (40)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Hollow inorganic film forming material microspheres of substantially uniform diameter of 200 to 10,000 microns and of substantially uniform wall thickness of 0.1 to 1,000 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said micro-spheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.

2. Hollow inorganic film forming material microspheres of substantially uniform diameter of 500 to 6,000 microns and of substantially uniform wall thickness of 0.5 to 400 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.

3. The hollow microspheres of Claim 2 having a contained gas pressure of above 50 p . s . i . g.

4. The hollow microspheres of Claim 2 having deposited on the inner wall surfaces thereof a thin metal coating.

5. The hollow microspheres of Claim 2 having an oblate spheroid shape.

6. Filamented, hollow inorganic film forming material microspheres having a diameter of 200 to 10,000 microns, having a wall thickness of 0.1 to 1,000 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same inorganic film forming material from which the microspheres are made.

7. Filamented, hollow inorganic film forming material microspheres having a diameter of 500 to 6,000 microns, having a wall thickness of 15 to 400 microns and having a contained gas pressure of above 15 p.s.i.g. at ambient temperature, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same inorganic film forming material from which the microspheres are made.

8. The hollow microspheres of Claim 7 having deposited on the inner wall surfaces thereof a thin metal coating.

9. The hollow microspheres of Claim 7 wherein the length of the connecting filaments is substantially equal and is 2 to 20 times the diameter of the microspheres.

10. The hollow microspheres of Claim 7 wherein the length of the connecting filaments is substantially equal and the diameter of the connecting filaments is 1/2500 to 1/20 the diameter of the microspheres.

11. Hollow glass microspheres of substantially uniform diameter of 200 to 10,000 microns and of substantially uniform wall thickness of 0.1 to 1,000 microns and having a contained gas pressure of above 15 p.s.i.g. at ambient temperature, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.

12. Hollow glass microspheres of substantially uniform diameter of 500 to 6,000 microns and of substantially uniform wall thickness of 0.5 to 400 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are free of latent solid or liquid blowing gas materials or gases and the walls of said microspheres are substantially free of holes, relatively thinned wall portions or sections, sealing tips and bubbles.

13. The hollow microspheres of Claim 12 having a contained gas pressure of above 50 p.s.i.g.

14. The hollow microspheres of Claim 12 having a high contained gas pressure above 100 p.s.i.g.

15. The hollow microspheres of Claim 12 having deposited on the inner wall surfaces thereof a thin metal coating 50 to 600°A
thick.

16. The hollow microspheres of Claim 12 having a diameter of 500 to 3,000 microns and a wall thickness of 0.5 to 200 microns.

17. The hollow microspheres of Claim 12 having an average bulk density of 0.5 to 10 lb/ft3.

18. A mass of the microspheres of Claim 12.

19. A molded form comprising a mass of the microspheres of Claim 18.

20. The hollow microspheres of Claim 12 having an oblate spheroid shape.

21. The hollow glass microspheres of Claim 11 having a diameter of 200 to 10,000 microns, a wall thickness of 10 to 1,000 microns and having a contained gas pressure of 15 to 6,000 p.s.i.g.
at ambient temperature.

22. The hollow glass microspheres of Claim 12 having a contained gas pressure of 100 to 1800 p.s.i.g., at ambient temperature.

23. The hollow glass microspheres of Claim 12 having a contained gas pressure of 800 to 1200 p.s.i.g., at ambient temperature.

24. The hollow glass microspheres of Claim 12 wherein the contained gas is a member selected from the group consisting of nitrogen, oxygen, hydrogen, carbon dioxide, methane and acetylene materials.

25. The hollow glass microspheres of Claim 23 wherein the contained gas is a stable acetylene gas.

26. The hollow glass microspheres of Claim 12 having a diameter of 500 to 2,000 microns, a wall thickness of 10 to 100 microns and a contained gas pressure of 15 to 1000 p.s.i.g., at ambient temperature.

27. The hollow glass microspheres of Claim 12 wherein the contained gas is radioactive and is a member selected from the group consisting of radon, tritium, krypton, xenon and iodine.

28. The hollow glass microspheres of Claim 12 having a diameter of 100 to 5,000 microns, a wall thickness of 1.0 to 500 microns and having a contained gas consisting of a member selected from the group consisting of tritium, deuterium, and mixtures thereof at a pressure of 200 to 2400 p.s.i.g., at ambient temperature.

29. The hollow glass microspheres of Claim 27 which are admixed with concrete to form a solid storage system.

30. Filamented, hollow glass microspheres having a diameter of 200 to 10,000 microns, having a wall thickness of 0.1 to 1,000 microns and having a contained gas pressure above 15 p.s.i.g. at ambient temperature, wherein said microspheres are connected to each other by filament portions which are continuous with the microspheres and are of the same inorganic film forming material from which the microspheres are made.

31. Filamented, hollow glass microspheres having a diameter of 500 to 6,000 microns, having a wall thickness of 0.5 to 400 microns, wherein said microspheres are connected to each other by filament portions which are continuous with the micro-spheres and are of the same inorganic film forming material from which the microspheres are made.

32. The hollow microspheres of Claim 31 having a contained gas pressure above 50 p.s.i.g.

33. The hollow microspheres of Claim 31 having a high contained gas pressure above 100 p.s.i,g.

34. A molded form comprising a mass of the microspheres of Claim 31.

35. The hollow microspheres of Claim 31 having an oblate spheroid shape.

36. The hollow microspheres of Claim 31 wherein the length of the connecting filaments is substantially equal and is 2 to 20 times the diameter of the microspheres.

37. The hollow microspheres of Claim 31 wherein the length of the connecting filaments is substantially equal and the diameter of the connecting filament is l/2500 to 1120 the diameter of the microspheres.

38. The hollow microspheres of Claim 31 having deposited on the inner wall surfaces thereof a thin metal coating 50 to 600°A thick.

39. The hollow microspheres of Claim 31 wherein the deposited metal is less than 100°A thick and is transparent to visible light.

40. The hollow microspheres of Claim 31 wherein the deposited metal is less than 100°A thick and is reflective of visible light.