CA1186130A

CA1186130A - Rigid, water-resistant phosphate ceramic materials and processes for preparing them

Info

Publication number: CA1186130A
Application number: CA000404306A
Authority: CA
Inventors: Jeffery L. Barrall
Original assignee: Armstrong World Industries Inc
Current assignee: Armstrong World Industries Inc
Priority date: 1981-06-16
Filing date: 1982-06-02
Publication date: 1985-04-30
Also published as: ES513168A0; FR2507591B1; SE455194B; IT1152973B; GB2100246B; NL186236B; NL186236C; HK25986A; GB2100246A; NL8202362A; SE8203688L; IT8221868A0; SG7686G; ES8305288A1; AU8466582A; DE3222078A1; DE3222078C2; AU544513B2; ES513167A0; FR2507591A1

Abstract

Abstract The present invention concerns rigid, water-resistant phosphate ceramic materials which may be prepared from components comprising metal oxide, calcium silicate, and phosphoric acid. By prereacting a portion of the metal oxide with the phosphoric acid and/or by adjusting the temperature of the acid solution when it is combined with the other ingredients, the character of the resulting product can be controlled to give foamed or unfoamed phosphate ceramic material.

Description

- ~L86~

RIGID, WATER-RESISTANT PHOSPHATE CERAMIC MATERlALS
AND PROCESSES FOR PREPARING THEM
.. . .

The present invention relates to rigid, water-resistant phosphate ceramic materials and more 10 particularly to rigid, water-resistant phosphate cera~ic materials which do not require subsequent thermal curing.
Background o the Invention Refractory metal phospha~es have long ~een recognized as useful building and insulatins materials.
Compositions comprising phosphoric acid, a metal oxide, and metal silicates are known in the art; however, composi~ions comprising these constituents and having adequate strength are extremely difficult to prepare.
For examplel mixtures of aluminum oxide and.85 phosphoric acid are viscous and difficult to handle. I~
such mixtures are diluted with water, the ease of handling is greatly improved; nevertheless, when silicate, e.g. calcium silicate, is added and the ~5 resulting phosphate is thermally cured to drive off excess water, the reractory material obtained has relatively poor tensile strength. Alternatively, if all . . . of the somponents are mixed to~ether at once without using additional ~ater, a rapid reaction ensues which ~1~

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- 2 - LFM-7149 cannot be handled under normal manufacturing circumstances.
The Prior Art Various phosphate compositions and processes for preparing them are found in the prior art. For example, U.S. Patent No. 2,992,930, dated July 18, 1961 to William Wheeler et al. discloses compositions comprising powdered zirconium or aluminum oxides, calcium silicate for foam stabilization, phosphoric acid, a silica sol bonding agent and a blowing agent, the composition being prepared by blending the dry ingredients, adding the silica sol, stirring the mixture with phosphoric acid and allowing the resulting foam to become rigid. U.S. Patent No. 3,148,996, dated September 15, 1964 to Mark Vukasovich et al. discloses compositions which set into a rigid mass without heating and which may be rendered porous by incorporation of gas bubbles~ These compositions consist of water, an acid phosphate consisting of phosphorus pentoxide and calcium, aluminum or zirconium oxides, and finely divided calcium silicate. They are formed by preparing a visCous solution of water, phosphorus pentoxide'and an appropriate metal oxide, adding calcium silicate to the mixture and allowing it to partially hardenO Foaming is then induced by adding an internal foaming agent or by mechanically introducing gas bubbles. U.S. Patent Wo.

3,330,675, dated July 11, 1967 to Jules Mag'der discloses compositions comprising acidic aluminum phosphate, the carbonate, oxide, hydroxide or silicate of magnesium or zirconium, and organic or inorganic gas producing materials~ Similarly, other patent references disclose related phosphate foams in which'a powdered metal is incorporated into the acidic mixture, thereby-inducing foaming through the release of hydrogen gas.
Although it is evident from these references that substantial effort has bee~ expended to develop useful phosphate foams, many-problems still exist. Most of the prior art foams have poor bond strength, thereby 3~

rendering them unusable as building materials. Some are moisture sensitive, many require heat curing to improve bond s~rength, and most contain other additives desi~ned to circumvent weakness problems; In addition, most commercially manufactured foams contain blowing agents which can increase the cost of the product and sometimes - contribute to bond weakness.
Accordingly, one object of the present invention is to provide strong, moisture-resistant phospha.e ceramic materials which can be prepared without the use of external heat.
Yet another object of the present invention is to provide processes for the preparation of rigid phosphate foams without the use of added blowing agents~
Still another object of the present invention is to provide processes for the convenient and continuous production of phosphate foam whereby slumping of the foam is avoided.
These and other advantages of the present invention will become a~parent from the description of the invention which follows.
Summary of the Invention The present invention concerns rigid, water-resistant phosphate ceramic materials which may be prepared Erom compohents comprising metal oxide, calcium silicate, and phosphoric acid. By prereacting a por~ion of the metal oxide with the phosphoric acid and/or by adjusting the temperature of the acid solution when it is combined with the other ingredients, the character of the res~lting product can be controlled to gi~e foamed or unfoamed phosphate ceramic material.
Detailed Descriptlon of Preferred Embodiments Xn one embodiment, the process of the present invention comprises the steps of (1) selecting at least one metal oxide from the group consisting of A12O3, MgOt CaO or ZnO or the hydrates thereof, said metal oxide comprising a total of from about 11 to about 65 parts by weight calculated on an anhydrous basis; (2) preparinq a 3~

_ 4 _ LFM-7149 reaction solution comprising a portion of said metal oxide and from about 80 to about 190 parts by weiqht oE
a phosphoric acid solution comprisinq the equivalent of from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included --- when calculating the phosphorus pentoxide content; (3) preparing a mixture comprisiny the remainder of said metal.oxide and about 100 parts by weight of calcium silicate. The temperature of said reaction solution is adjusted to a desired value and the mixture is prvportionally intermixed with said reaction solution.
The resulting intermixed material is placed in a desired configuration and the components thereof are allowed to interact. The amount of metal oxide used to prepare the reaction solution and the temperature of the reaction solution are selected s~ as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs.
In a second embodiment the process of the present invention comprises the steps of (i) preparing a mixture comprising from about ll to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consistinq of Al2O3, MgO, CaO or ZnO or the hydrates thereof, and about 100 parts by weight of calcium silicatè; and (2) preparing a reaction solution comprising from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent oE from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content. The temperature of the reaction solution is adjusted to a desired value and the solution is proportionally .intermixed with said mixture. The resulting intermixed material is placed in a desired configuration and the components thereof are allowed to -, ' - 1~86~30 interact The temperature of the reaction solution is selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs.
In a third embodiment the present invention comprises the steps~of (1) selecting at least one metal oxide from the group consisting of A12O~, MgO, CaO or ZnG or the hydrates thereof, said metal oxide comprising a total of from about 11 to about 65 parts by weight calculated on an anhydrous basis; (2) preparing a reaction solution comprising a portion of said metal oxide and from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75~ by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said met~l oxide bein~ included whèn calculating the phosphorus pentoxide content; and (3) preparing a mixture comprising the remainder of said metal oxide and about 100 parts by weight of calcium silicate. The mixture is proportionally intermixed with said reaction solution and the resulting intermixed material ls placed in a desired configuration where the components thereof are allowed to interact. The amount of metal oxide which is used to prepare the reaction solution is selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporiæation of the water occurs.
In a fourth embodiment the present invention comprises a composition suitable to provide a rigid, water-resistant ~hosphate ceramic material, said composition comprising (1) from about 11 to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consistinq of A12O3, MgO, ~aO or ZnO or the hydrates thereof; (2) 6~3~P

6 - LFM-7l49 from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water o hydration of said metal oxide being included when calculating the phosphorus pen'oxide content; and (3) about 100 parts by weight of calcium silicate.
In a fifth embodiment the present invention comprises a rigid, water-resistant phosphate ceramic material obtained by reacting (1) from about ll to about 65 parts by weight calculated on an anhydrous basis of at leas-t one metal oxide selected from the group consisting of A12O3, MgO, CaO or ZnO or the hydrates thereof, (2) fr~m about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content; and (3) about 100 parts by weight of calcium silicate.
The components used to practice the present invention are all commercially available. Calcium silicate (100 parts by weight) is preferred in practicing the present invention although other silicates may also give satisfactory results. Calcium silicate occurs naturally and is referred to as wollastonite. Suitable foamed or unfoamed products can be obtained when this material is used in powdered form as described belo~. For making foams, the particle size will preferably be sufficiently small that most of the silicate passes through a 200-mesh Tyler Standard sieve.
A numher of metal oxides su~h as aluminum oxide, magnesium oxide, calcium oxide and zinc oxide may be used to obtain satisfactory phosphate ceramic material. These oxides are used in powdered ~orm, with finer particle-size oxides on the order oE 325 mesh (Tyler Standard) or slnaller givin~ generally superior ~86~3~1 results. Hydrated forms of the oxide may also be u.sed and in many instances are preferred. In the event that a hydrate is used, the water of hydration must be taken into account so as not to provide excess water for the reaction. This may be conveniently done by including the water of hydration when calculating the phosphorus pentoxide content of the phosphoric acid solution.
From about 11 to about 65 parts by weight of metal oxide, calculated on an anhydrous basis, in relation to 100 parts of calcium silicate may be used to practice the present invention; however, from about 13-26 parts of metal oxide is preferred and from about 15-20 parts is especiall~ preferred. The amount of oxide which is used will depend on whether it is in hydrated form and/or on its reactivity.
Anhydrous magnesium oxide reacts much more rapidly with phosphoric acid than does anhydrous aluminllm oxide. For example, the former will react within minutes whereas the latter may require hours, depending on the temperature of the acid solution If hydrated forms are used, however, the disparity in the reaction times is dramatically dimini.shed. Hydrated magnesium oxide reacts more quickly than does anhvdrous magnesium oxide, and it also reacts much more auickly than hydrated aluminum oxide Nevertheless, hydrated aluminum oxide is substantially more reactive than anhydrous aluminum oxide for it reacts with the `
phosphoric acid solution within a matter of minutes, rather than hours. The implications of the reaction times will be set forth more ~ully below.
Suitable products can be obtained using any of the indicated oxides, alone or in combination, bùt anhydrous magnesium oxide (calcined) and hydrated aluminum oxide are particularlv preferred to practic~
tne present invention. Magnesium oxide tends to increase the strength and moisture resistance o~ the ~inal product whereas aluminum oxide tends to provide superior settin~ characteristics~

~:~86~3~

- 8 - LF~-7149 Phosphoric acid is availa~le in a variety of concentrations, 85% being the most common concentration for ortho-phosphoric acid. Other compositions, such as polyphosphoric acid, which will yield phosphoric acid upon dilution with water may also be satis~actory to practice the present invention, provided that the overall water content of the reaction system is not too high. Tov much water must be avoided because products will be obtained which, even though water resistant, will have poor strength. On the other hand, too little water is also detrimental, not only because intermixing of the materials is difficult to achieve, but hecause, in the case of foamed products, only hiqh density foams are obtained.
As a ~eneral rule, the phosphoric acid will be suitable if it contains tlle equivalent oE from about 35 to about 75~ by weight of phosphorus pentoxide based on the weight of the acid solution. Preferably, the equivalent of phosphorus pentoxide will be about 40-70~, and more preferably about 4S-65%. The remaining portion of the acid solution comprises water including, for purposes o calculation, any water of hydration from the metal oxide. From about 80 to about 190 parts by weight of the acid solution may be used in practicing this invention but preferably from about 90 to about 150 parts will be used, and more preferably from about 100 to about 130 parts of acid will be used.
Although the components used to practice the present invention have long been used in the art, the advantages to be derived when these components are combined as disclosed herein have never been recognized.
It has been discovered that if the manner in which the ingredients are combined is controlled and excess water is avoided, a product will be obtained which requires no 3S heat curing and is water resistant. While applicant is not bo~nd by any theory as to thè nature oE the reactions involved in the present invention, two separate yet related phenomena are apparently . ... .. .

3~ -'.
- g - LFM 7149 occurrin~; namely, vaporization of the water and bonding of the materials. Heat generated by the reactants vaporizes the water present whereby the water vapor can act as a foaminq agent~ During approximately the same time span, bonding or setting occurs which results in the formation of a rigid ceramic-like material. These two phenomena will be referred to herein as "vaporization" or the "vaporization stage,"
and "setting" or the "setting stage," respectively.
To practice the present invention a reaction solution is preferably prepared by addinq a desired portion of the metal oxide to the phosphoric acid solution. In addition, liquid additives such as surfactants may also be incorporated into the reaction solution. The remainder of the metal oxide and all of the calcium silicate are then combined and mixed with any solid additives, such as reinforcing fibers, thickeners, coloring matter and the like. The temperature of the reaction solution is preferably adjusted to a desired value and the solution is proportionally mixed with the remaining dry ingredients.
The intermixed material is then placed in a desired configuration and the components of the system interact.
The products which are obtained do not require heat curing and may be placed in boiling water without adverse effect. Nevertheless, they are not heat sensitive for samples have been heated to 1600F without significant loss of strength.
It has been discovered that the relative points in time at which vaporization and setting occur will dictate the nature of the product which is obtained. For-example, if the vaporization stage is reached before the setting stage, the water vapor will cause the mixture to foam before the mass becomes rigid.
Conversely, if setting occurs first, the material is unable to foam and the water vapor escapes through the interstitial spaces. The implications of the latter se~uence of events will be set forth in more detail , below, but in either case a product can be obtained which does not require heat curing, yet is resistant to water.
Two factors which contribute to the aforementioned events are the amount of metal oxide which is prereacted with the phosphoric acid and the temperature of the reaction solution at the time it is combined with the remaining dry ingredients. If only one of these factors is controlled, a c~ramic-like mater1al can still be produced. Nevertheless, it is preferable to control both parameters to facilitate handling and to obtain a superior prbduct.
~ ow these factors may be varied will be seen Erom the followinq. Generally speaking, if relativelv less of the metal oxide is prereacted with the phosphoric acid, relatively more foaming will occur during the subsequent mixing step before the mass of materials become rigid, provided that the temperature o the acid solution is not too low. Conversely, if 29 relatively more of the metal oxide is prereacted with the phosphoric acid, less foaming will occur before the mass beco~es rigid. If enough metal oxide is prereacted, essentially no foaming will occur. This result i~ apparently obtained because the preaddition of the metal oxide tends to lengthen the duration of the - exothermic reaction or reactions which vaporize the water.
- The temperature of the reaction solution during the subsequent mixing step can also siqnificantly affect the resulting product. The higher the temperature of this soluti~n, the more vigorous is the evolution of water vapor and the sooner water vaporization occurs when the reaction solution is mixed with the remaining dry ingredients. Thus, if the temperature is too high, the greater the likelihood of obtaining foams wKich contain voids or wnich foam rapidly and then slump. This effect may be mitigated somewhat, however, by including a surfactant in the reaction solution.

.

6~3~D

If the temperature is too low, the exothermic reaction may be suppressed so that no foaming will occur. Furthermore, too low a temperature may be detrimental because the material which is obtained might have relatively weak bonding strength~ The optimum temperature of the reaction solution can vary depending on the reactants, but generalIy it has been found that a tempera~ure range of about 35 to about 80F will give satisfactory results. When making foams, the preferred temperature range is about 38-45F, and most preferably 40F, unless a foaming agent is added as hereinafter set forth.
In practice, other factors in addition to the amount oE prereacted material and the temperature of the acicl solution must be considered, many of which are dependent on the type of product to be produced. When making foams, the objective is to cause the foam to reach a desired height at about the time setting occurs.
In essence, the water vaporization which causes the foaming should be timed so that it yields a uniform cell size in a product which is the right height and density after settiny is complete. Cell size is affected bv the rate at which the water vapor is given off and by the viscosity of the acid solution. The viscosity, in turn, depends on the type of oxide or oxides used, the particle si~e of the oxide, and the temperature of the acid solution.
Solutions having different viscosities are obtained when the various oxides are dissolved in phosphoric acid. For example, when increasin~ amounts of magnesium oxide are added to one aliquot of a standard strength ~e.g. 85~) acid solution, viscosities are observed to vary from ca 50 cp to l,OOO cp at 72F.
However~ when comparable ~olar amounts of aluminum oxide are added to a second aliquot of the same acid solution at 72F, viscosities of from ca 50 cp to only 400 cp are observedO To make superior foams, it is preferred that the viscosity of the acid solution at the time of ~86~3~

intermixing with the remaining ingredients not exceed about 400 cp. Thus, it will be seen that a second limitation to the use of magnesium oxide, aside from its tendency to vigorously cause foaming, i5 the viscosity of the reaction solution whic:h results when it is used.
~ The higher the viscosity of the reaction so~ution the poorer the mixing of the ingredients and the poorer the foam quality oE the product that is obtained. For that reason~ it is often desirable to use more than one oxide. Thus, one oxide could be used to prepare the reaction solution and another could be combined with the calcium silicate. Alternatively, the oxide could be used as a mixture, both for forming the reaotion soIution and for mixin~ with the calcium silicate. A variety of possibilities exist; therefore, it is intende~ that all such possibilities be included within the scope of the present invention, and the present invention should not be limited to these two illustrations.
The density of the final product will depend to a great extent on the amount of metal oxide which is used to form the reaction solution; namely, the more of the metal oxide, ~he greater the density. As a general rule, in the absence of added foaming agents, if from about 0 to about 0.3 part of metal oxide for each one part of P2O5 in the acid solution is used to form the reaction solution, foams having densities of fro~ about 40 down to about 15 pounds per cubic foot will be obtained. However, if more than about 0.3 part of metal oxide i5 used, a non-foamed ceramic will be anticipated. Nevertheless, practical considerations, such as viscosity, afect the upper limit of prereacted material; thus, usually not more than 50% of the metal oxide can be conveniently prereacted.
Other considerations which aEfect the foams are pàrticle size, surface properties and reinforcing materials. A small and uniform particle siæe is ~uch preferred to practice the present invention because o~

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the tendency of such material to promote fine cell structure. As previously note~l, metal oxides which pass throu~h a 325-mesh Tyler Standard sieve and calcium silicate which passes throu~h a 200-mesh Tyler Standard sieve are preferred.
Cell size also de]pends on the sur~ace properties of the material and it is often helpful to include one or more surfactants to promote cell stabilityO Virtually any surfactant which is not affected by the phosphoric acifl may be used. One surfactant which has been found particularly satisfactory is dimethylcocamine oxide which is sold by Armak under the name Ara~ox DMC. Care must be taken in handling this material, however, because it is a skin and eye irritant.
Because foams are of a porous nature, they tend to have lower tensile strength than unfoamed materials~ Accordingly, it is often advisable to add fibrous reinforcing material to strengthen the foam.
Polyester, glass, polypropylene and nylon, among others, have been used with success, although the conditions under which the final product will be used may influence the selection ffl fiber. For example, for a high temperature application, glass fibers would be much more stable than would organi~ fibers. Generally, fiber lengths of from 1/8" to 1" will be sui~able, with approximately 1/2" fibers being especially suitable~
When preparing unfoamed phosphate ceramics, factors such as particle size, viscosityr tem~erature and surface properties become much less important because c:ell structure is not a concern. Accordinqly, coarser particle-si~e materials and a higher viscosity of the reaction solution may be permissible~ subject only to constraints imposed by the handleability of the reactants. A much higher temperature for the reaction solution may also be used becaose the unfoamed material will not slump. Furthermore, no surfactant will be required because there is no cell stability problem.
*Trademark , ~
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.

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Aside from these considerations, the objective in preparing an unfoamed ceramic is comparable to that of preparing a foamed material, the major diference being that, with unfoamed materials, it i5 necessary to postpone the vaporization stage until the mass has become rigid, thus preventing expansion of the phosphate material. This is convenien~ly accomplished by prereacting a greater amount of the metal oxide.
However, care must be taken to ensure that the water can escape from the unfoamed material. If the internal pressure of the structure becomes too great due to water pressure, the rigid ceramic can be cracked~ For this reason, when preparing unfoamed phosphate ceramics, it is often desirable to include porous fillers which provide passageways through which the water vapor can escape. Examples of fillers which are satisfactory are vermiculite and perlite.
Surprisingly, I have also discovered that satisfactory foamed products may be produced by combining the techniques of the present invention with foaming agents taught by the prior art. The prior art contains references to the use of carbon dioxide or carbon dioxide-producing materials and hydrogen or hydrogen-producing materials, as well as other organic or inorganic gas-producing materials, durin~ the production of phosphate products. Such aqents may also be used to advantage in producing the rigid, water-resistant phosphate ceramics of the present invention.
Although virtually any prior art foaming agent may be employed, the results that may be obtained are exemplified by the use of various carbonates.
Carbonates such as MgCO3, CaC03, ZnC03, Li2C03 and the like, or mixtures thereof, which produce .elatively insoluble phosphates are preferred; however, MgCO3 is especially preerred be~ause it typically produces a foam having a relatively uniorm cell size and a generally suitable denslty. Other carbonates such as 3 and K2C03 which produce relatively soluble ~6~3~

phosphate salts may also be employed where leaching of the phosphate from the resulting phosphate ceramic when it is exposed to water will not be detrimental~
~hen using dry foaming agents, it is usually desirable to mix them with the other dr~ ingredients comprising the calcium silicate and a portion of the metal oxide; however, these foaming agents may also be added'separately. Because the foaming obtained in the presence of such agents is not provided by water vaporization, it is undesirable to have the exotherm occur prior to setting. For that reason, it is usually necessary to prereact a greater portion of the metal oxide'with the phosphoric acid solution. Often this will cause an undesirable increase in the viscosity of 15 the acid solution. Accordingly, when using an added ;~
foaming agent, it may be necessary to dilute the aci~
solution somewhat in order to control the viscosity.
~owever, care must be taken to avoid usin~ excess water because the combination of using additional water and prereacting more of the metal oxide tends to lower the temperature of the exotherm, thereby increasing the possibility of producing a phosphate ceramic with unsati~factory performance characteris~ics.
As an additional consideration, the temperature'of the reaction solution at the time of intermixing with the dry components can o~ten be higher when foaming is achieved using dry foaming agents rather than using water vaporization because setting must occur prior to the occurrence of the exothermic reaction.
Thus, when using dry foaming agents, it is often desirable for the reaction solution to be within a preferred temperature range of about 50 to 6noF rather than the preferred range of about 38 to 45F referred to earlier in connection with the water vaporization foaming process.
Of course, it is also possible to use a li~uid foaming agent such as a fluorinated hydrocarbon having a boiling point lower than the temperature at which 36~3~

setting of the foam occurs. Examples of such hydrocarbons are Freon-ll or Freon-113 sold by duPont.
~ydrocarbons of this type may be added to and mixed with the acid solution, or they may be added separately at 5 th~ time of intermixing Witil the solid ingredients.
Non~fluorinated hydrocarbons having an appropriate boiling point may also be u~ed, but they are much less desirable because of the inherent risk of fire associated with their use.
~he manner of adding these foaming agents, whe~her wet or dry, may be a matter of choice to the artisan or it may depend on various factors such as the type of product desired and/or the type of equipment utilized. In certain circumstances, the method of use may be controlled by the nature of the foaming agent.
For example, the carbonates react chemically with the acid solution; thus, they cannot be added to the acid solution at a point too early in the reaction sequence.
Conversely, fluorinated hydrocarbons produce foaming by passing from a liquid to a gaseous state; thus, they may be maintained in contact with the acid solution if the temperature of the mixture remains sufficiently low. In the lat~er case, however, it must be recognized that - fluorinated hydrocarbons form a two-phase system with the acid solution. Therefore, care should be taken to ensure that the two-phase system is uniformly mixed prior to intermixing with the solid ingredients.
Because the art discloses a wide variety of materials which may be employed in various ways to produce t:he phosphate ceramics of the present invention, the term "foaming agent~,~ as used herein, is intended to encompass all such materials, provided that thev produce phosphate ceramics having the characteristics previouly set forth.
The following examples, in which all parts are expres~ed by weight, will be illustrative to Aemonstrate the advantages of the present invention.

*Trademark ~86:~L3~

~X~MPLES
Examl?le 1 A phosphate foam was prepared from the following components:
Parts per W ~ ~ 100 parts CaSlO~
23.3H2 14.42 3~.04 85% H3P4 41.58 104~0 ~61.~% P2O5~
CaSiO3 40.0 100 Surfactant 0.04 0.1 If these relationships are calculated by placing the metal oxide on an anhydrous basis and includiny the water of hydration as part of the acid solution, the followinq is obtained:

Parts per 100 Component Parts CaSi~3 Al23 23.56 75,9~ H3P4 116.5 Z0 ~ ~55% P2Os) CaSiO3 100 Surfactant 0.1 The reaction solution was prepared by adding 1.04 parts of Al2O3~3~2O to 104 parts of phosphoric acid and stirring the mixture with moderate agitation for approximately 15 minutes until a clear solution was obtained. The surfactant (0.1 part) was added to the reaction solution, which was then cooled tG 40F. The remaining dry ingredients (100 parts of calcium silicate and 35 parts of a~uminum oxide trihydrate~ were mixed together and fed into a Readco continuous processor.
The reaction solution was also fed into -the ~eadco mixer through a different addition port. The ingredients were proportionally mixed therein, dischar~ed onto a ~ovinq *Trademark ~L~86~3~

belt covered with a scrim material and leveled. Foaming began in approximately 1.5 minutes and the mass of material became rigid in approximately 2 minutes. A
continuous block of foamed material 1 thick and 5 wide was obtained in this manner. The foamed material had a fine cell structure and a density of 18 pounds per cubic foot The compressive strength of this material according to ASTM D1621 was 60 psi. The modulus of rupture according to ASTM C209 was 70 psi. No evidence of cracking was detected when 20-g cubes of the product were either placed in boiling water for l/2 hour and allowed to dry~ or wetted with 50 g of water at room temperature and allowed to dry.
Example 2 ` ~ phosphate foam was prepared from the same components used in Example l. The reaction solution was prepared by adding 1.04 parts of A12O3.3H2O to 104 parts of phosphoric acid and stirring the mixture with moderate agitation for approximately 15 minutes until a clear solution was obtained. The surfactant (0~1 part) was then added to the reaction solution. The remaining dry ingredients (lO0 parts of calcium silicate and 35 parts of aluminum oxide trihydrate) were mixed to~ether and fed into a Readco continuous processor. The reaction solution at room temperature, 7~F, was also fed into the Readco mixer through a different addition port. The ingredients were proportionally mixed therein, discharged onto a moving belt covered with a scrim material and leveled. Foaming began in approximately 42 seconds and the mass of material became rigid in approximately 50 seconds. A continuous block of foa~ed material 1' thick and 5" wide was obtained in this manner~ The foamed material had a coarse, irregular cell structure and a density of 17 pounds per cubic foot. The compressive strength of this material according to ASTM Dl621 was 50 psi. The moclulus o~
rupture according to ASTM C209 was 50 psi. No evidence oE craclcing was detected when 20-q cubes o~ ~he product 6~1L30 - 19 - LFM~7149 were either placed in boiling water for 1/2 hour and-allowed to dry, or wetted with 50 9 of water at room temperature and allowed to dry.
F.xample 3 A phosphate foam was prepared from the following components:
,= . .. -Parts per Component Weight (g) 100 parts CaSiO~
A123~3H2 11.44 30.1 MgO (~alcined) 3.0 7.9 80% H3P04 43~56 114.63 (58.0% P20S) CaSiO3 3~ 100 Surfactant 0.3, 0.79 15 1/2" Polyester Fiber 0.2 0.53 , If these relationships are calculated by placing the metal oxide on an anhydrous basis and including the water of hydration as part o~ the acid solution, the following is obtained:
:
Parts per 100 Component Parts CaS io~

~123 19.7 MgO tcalcined) 7.9 73-3% ~3P04 125,05 (53.~ P20s) CclSiO3 100 Surfactant 0.79 lf2" Polyester Fiber 0.53 , .
The reaction solution was prepared by adding 1.15 parts of A1203.3H20 to 114.63 parts of phosphoric acid and stirring the mixture-with moderate agitation for approximately 15 minutes until a clear solution ~1as obtained. The surfactant (0.79 part~ was added to the .. ..

361;~

- 20 - LF~-7149 reaction solution, which was then cooled to 40F. The remaining dry ingredients (100 parts of calcium silicate, 28.95 parts of aluminum oxide trihydrate, 7.9 parts of magnesium oxide and 0.53 parts polyester fiber) were mixed together~and fed into a Readco continuous processorO The reaction solution was also fed into the - Readco mixer through a different addition port. The ingredients were proportionally mixed therein, discharged onto a moving belt covered with a scrim material and leveled. Foaming began in approximately 57 seconds and the mass of material became rigid in approximately 1 minute 51 seconds. A continuous block of-foamed material 1" thick and 5" wide was ob~ained in this manner. The foamed material had a Eine cell structure and a density of 19 pounds per cubic foot.
The compressive strength of this material according to AST~. D1621 was 100 psi. The modulus of rupture according to ASTM C209 was 80 psi. No evidence of cracking was detected when 20-g cubes of the product were either placed in boiling water for 1/2 ho~lr and allowed to dry, or wetted with 50 g of water at room temperature and allowed to dry.
Example 4 A phosphate foam was prepared from the following components:
Parts per Component Weight (g)100 parts CaSiO~
A12O3.3H2o 16.0 40.0 ~5~ 1~3PO4 40.0 1~0.0 (61.6% P2Os) CaSiO3 40.0 100.0 Surfactant 0,04 0.1 If these relationships are calculated by placing the metal oxide on an anhydrous basis and inclu~ing the water of hydration as part of the acid solution, the following is obtained:

-~6~3il~
-Parts per 100 Component Parts CaSiO3 _ ~ .

A123 26.15 74.7~ H3PO~ 113.85 (54.1~ P2O5) CaSiO3 100 Surfactant 0.1 The reaction solution was prepared by adding 5 parts of Al2O3.3H2O to 100 parts oE phosphoric acid and stirring the mixture with moderate agitation for approximately 15 minutes until a clear solution was obtained. The surfactant t0.1 part) was added to the reaction solution, which was then cooled to 40F. The remaining dry ingredients (100 parts of calcium silicate and 35 parts of aluminum oxide trihydrate) were mixed together and fed into a Readco continuous processor.
The reaction solution was also fed into the Readco mix~r through a different addition port. The ingredients were proportionally mixed therein, discharged onto a moving belt covered with a scrim material and leveled. Foaming began in approximately 1 minute 45 seconds and the mass of material became rigid in approximately 2 minutes 5 seconds. A continuous block of foamed material 1" thick and 5" wide was obtained in this manner. The foamed material had a fine cell structure and a density of 29 pounds per cubic foot. The compressive strength of this material according to ASTM D1621 was 120 psi. The modulus of rupture according to ASTM C209 was 120 psi.
No evidence of cracking was detected when 20-g cubes of the product were either placed in boiling water for 1/2 hour and allowed to dry, or wetted ~ith 50 g of water at room temperature and allowed to dry.
Example 5 A non-foamed phosphate ceramic was prepared from t~e following components:

~3613~

Parts per Component Weight (g) 100 parts CaSiO3 A123.3H2 18.4 40.89 85~ H3PO4 39.6 88.0 ~61.6% P2O5) CaSiO3 45.0 100 If these relationships are calculated by placing the metal oxide on an anhydrous basis and including the water of hydration as part of the acid solution/ the following is obtained:

Parts per 100 Component Parts CaSiO~

A123 26.73 73.2% H3PO4 102.16 (53.1% P2Os) CaSiO3 100 The reaction solution was prepared by adding 9.78 parts of A12O3-3H2O to 88 parts of phosphoric acid and stirring the mixture with moderate agitation for approximately 15 minutes until a clear solution was obtained. The remaining dry ingredients (100 parts of calcium silicate and 31.1 parts of aluminum oxide trihydrate) were mixed together and fed into a Readco continuous processor. The reaction solution at room temperature was also fed into the Readco mixer throuyh a different addition port. The ingredients were proportionally mixed therein, discharyed onto a movinq belt covered with a scrim material and leveled. No foaming occurred and the mixture set into a solid mass in 2 minutes 10 seconds. The hard ceramic-like ma~erial had a density of 60 pounds per cubic foot.
~xample 6 A phosphate ceramic was prepared from the followiny components:

6~

Parts per Co~ponent Weight (g) 100 parts CaSi~3 A12O3.3H20 17.44 38.76 72% H3PO4 40.56 90.13 t52.18% P2Os) CaSiO3 45 100 --- ~ Vermiculite (6#/ft3) 4 8.ag If these relationships are calculated by placing the metal oxide on an anhydrous hasis and including the water of hydration as part of the acid solution, the following is obtained:

Parts per 100 Component Parts CaSiO~
A1~03 25.34 63% H3PO4 103.55 (45.4% P2Os) CaSiO3 100 Vermiculite 8.~9 The reac~ion solution was prepared by adding 7.65 parts of ~12O~.3H2O to 90.13 parts of phosphoric acid and stirring the mixture with moderate agitation for approximately 15 minutes until a clear solution was -obtainecl. The remaining dry ingredients (100 parts of-calcium silicate, 31.11 parts of aluminum oxide trihydrate and 8.89 parts of vermiculite) were mixed together and fed into a Readco continuous-processor.
The reaction solution at room temperature (72F) was also fed into the Readco mixer through a different addition port. The ingredients were proportionally mixed therein, discharged onto a moving belt covered with a scrim material and leveled. No foaming occurred and t~e mixture set into a solid mass in 2 minutes 30 seconds. The hard ceramic-like material had a density of 59 pounds per cubic foot.

6~3~

Example 7 This example illustrates the use of a prior art dry foaming agent in combination with the present invention to produce a phosphate ceramic material. A
phosphate foam was prepared from the following components:
Parts per ComponentWeigh_ tg)100 parts CaS _~
A1203.3H20 8.97 17.94 68% H3PO~
(4g.3% P2O5) 56.03 112.0 CaSiO3 50.00 100.0 MgCO3 2.0 4.0 MgO (calcined) 7.0 14.0 Talc Filler10.0 20.n If these relationships are calculated by placing the metal oxide on an anhydrous hasis and including the water of hydration as part of the acid solution, the following is obtained:

Parts per Component 100 parts CaSiO~
A123 11.72 64.4% H3PO4 (46.7% P2Os) 118.27 CaSiO3 100.0 MgC03 MgO (calcined~ 14.0 Talc Filler 20.0 The reaction solution was prepared at room temperature by adding 17.94 parts of A12O3.3H2O with stirring to 112.06 parts of phosphoric acid solution.
The resulting elear solution was cooled to 55 F. The remaining dry ingredients (100 part~s of calcium silicate, 4.0 parts of magnesium carbonate, 14.0 parts of magnesium oxide and 20.0 parts o~ ~iller) were mixed .

~.~L8~ 3~l together and fed into a Readco continuous processor.
The reactLon solution at 55G F was also Eed into the - Readco mixer through a different addition port. The inyredients were proportionally mixed therein, and 5 discharged onto a moving belt covered with a scrim material. Due to the presence of the acid in the mixture, foaming was occurring as the material exited the mixer. The foamin~ material was leveled and it solidified in approximately l minute 30 seconds, with an exothermic reaction occurring approximately 30 seconds thereafter as indicated by the evolution of steam. The rigid foamed material had a fine cell structure and a density of 12 pounds per cubic foot. The compressive strength of this material according to ASTM Dl621 was 90 pounds per square inch and the modulus of rupture according to ASTM C209 was 40 pounds per square inch.
This material floated when placed in water, indlcatlng that the water could not readilY penetrate the foam matrix.
Example 8 This example illustrates the use of a liquid prior art foaming agent to produce the phosphate ceramic of the present invention. A phosphate ceramic was prepared from the following cbmponents:
Parts per ComponentWeight (g)100 parts per CaSiO~
A1203-3H20 9 0 18.0 ~0.2% ~3PO4 (58~2% P2Os) 53.0 106~0 CaSiO3 50.0 100.0 Freon-ll 4.0 8.0 MgO (calcined) 5.0 10.0 Talc Filler10.0 20.0 If these relationships are calculated by placing the metal oxide on an anhydrous basis an~
including the water of hydratlon as part of the acid solution, the following is obtained:

L3~

- 26 -LFm~7149 Parts per Component 100 parts Ca.~ 3 A123 11.8 75.8% H3Po4 ~55% P2O5) 112.2 CaSiO3 100.0 Freon-ll 8.0 MgO (calcined) 10.0 Talc Filler 20.0 The reaction solution was prepared at room temperature by mixing 10 parts of ~1~03.3~0 with stirring to 106.0 parts-of phosphoric acid solutionj after which the reaction solution was cooled to 55 F.
Thè remaining dry ingredients (100 parts of calcium silicate, 8.0 parts of aluminum oxide trihydrate, 10.0 parts of magnesium oxide and 20.0 parts of filler) were mixed together and fed into a Readco continuous processor. The ingredients were proportionally mixed therein, the Freon-ll being added through a separate in-line mixer in order to obtain good dispersion. The intermixed material exited from the -,nixer and foaming occurred slowly over a 3-minute period. Solidifaction occurred in 4 minutes, and the exothermic reaction occurred in 4~5 minutes. The resulting coarse-celled foam had a density of 19 pounds per cubic foot.
My invention is not restricted solely to the descriptions and illustrations provided above, but encompasses all modifications envisaged by the following claims.

Claims

I CLAIM:

1. A process for manufacturing rigid, water resistant phosphate ceramic material, said process comprising the steps of:
preparing a metal oxide comprising from about 11 to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consisting of A12O3, MgO, CaO or ZnO or the hydrates thereof, preparing a reaction solution comprising a portion of said metal oxide and from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75%
by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content, preparing a mixture comprising the remainder of said metal oxide and about 100 parts by weight of calcium silicate, adjusting the temperature of said reaction solution to a desired value, proportionally intermixing said mixture with said reaction solution, and placing the resulting intermixed material in a desired configuration and allowing the components thereof to interact, the amount of metal oxide used to prepare the reaction solution and the temperature of the reaction solution being selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs.

2. The process according to claim 1 hereof comprising from about 13 to about 26 parts of metal oxide, about 100 parts of calcium silicate, and from about 90 to about 150 parts of phosphoric acid solution comprising the equivalent of from about 40 to about 70%
phosphorus pentoxide.

3. The process according to claim 1 hereof comprising from about 15 to about 22 parts of metal oxide, about 100 parts of calcium silicate, and from about 100 to about 130 parts of phosphoric acid solution comprising the equivalent of from about 45 to about 65 phosphorus pentoxide.

4. The process according to claims 1, 2, or 3 hereof wherein the temperature of the reaction solution is from about 35 to 80° F.

5. The process according to claims 1, 2, or 3 hereof wherein the temperature of said reaction solution is from about 38 to 45° F.

6. The process according to claims 1, 2, or 3 hereof wherein the temperature of said reaction solution is about 40° F.

7. The process according to claims 1, 2, or 3 hereof wherein the particle size of said metal oxide is not larger than 325 mesh (Tyler Standard) and the particle size of said calcium silicate is not larger than 200 mesh (Tyler Standard).

8. The process according to claims 1, 2, or 3 hereof wherein said metal oxide is aluminum oxide trihydrate.

9. The process according to claims 1, 2, or 3 hereof wherein said metal oxide is magnesium oxide.

10. The process according to claims 1, 2, or 3 hereof wherein said metal oxide comprises a mixture of aluminum oxide trihydrate and magnesium oxide.

11. The water resistant phosphate ceramic product of the process set forth in claims 1, 2, or 3 hereof.

12. The products according to claim 11 hereof wherein said products have a foamed structure.

13. The products according to claim 11 hereof wherein said products have an unfoamed structure.

14. The products according to claim 13 hereof wherein said products comprise a filler.

15. The process according to claims 1, 2, or 3 hereof wherein said reaction solution comprises a surfactant.

16. The process according to claims 1, 2, or 3 hereof wherein said mixture comprises fibrous reinforcing material.

17. The process according to claims 1, 2, or 3 hereof wherein said intermixed material comprises a foaming agent.

18. The process according to claims 1, 2 or 3 hereof wherein said intermixed material comprises a foam-ing agent which is a carbonate selected from the group consisting of MgCO3, CaCO3, ZnCO3 or Li2CO3.

19. The process according to claims 1, 2 or 3 hereof wherein said intermixed material comprises a foaming agent which is a fluorinated hydrocarbon having a boiling point lower than the temperature at which said intermixed material becomes rigid.

20. A process for manufacturing rigid, water resistant phosphate ceramic material, said process comprising the steps of:
preparing a mixture comprising from about 11 to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consisting of Al2O3, MgO, CaO, or ZnO or the hydrates thereof and about 100 parts by weight of calcium silicate, preparing a reaction solution comprising from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content, adjusting the temperature of said reaction solution to a desired value, proportionally intermixing said mixture with said reaction solution, and placing the resulting intermixed material in a desired configuration and allowing the compounds thereof to interact, the temperature of the reaction solution being selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs.

21. The process according to claim 20 hereof comprising from about 13 to about 26 parts of metal oxide, about 100 parts of calcium silicate, and from about 90 to about 150 parts of phosphoric acid solution comprising the equivalent of from about 40 to about 70%
phosphorus pentoxide.

22. The process according to claim 20 hereof comprising from about 15 to about 22 parts of metal oxide, about 100 parts of calcium silicate, and from about 100 to about 130 parts of phosphoric acid solution comprising the equivalent of from about 45 to about 65 phosphorus pentoxide.

23. The process according to claims 20, 21, or 22 hereof wherein the temperature of the reaction solution is from about 35 to 80° F.

24. The process according to claims 20, 21, or 22 hereof wherein the temperature of said reaction solution is from about 38 to 45° F.

25. The process according to claims 20, 21, or 22 hereof wherein the temperature of said reaction solution is about 40°F.

26. The process according to claims 20, 21, or 22 hereof wherein the particle size of said metal oxide is not larger than 325 mesh (Tyler Standard) and the particle size of said calcium silicate is not larger than 200 mesh (Tyler Standard).

27. The process according to claims 20, 21, or 22 hereof wherein said metal oxide is aluminum oxide trihydrate.

28. The process according to claims 20, 21, or 22 hereof wherein said metal oxide is magnesium oxide.

29. The process according to claims 20, 21, or 22 hereof wherein said metal oxide comprises a mixture of aluminum oxide trihydrate and magnesium oxide.

30. The water resistant phosphate ceramic product of the process set forth in claims 20, 21, or 22 hereof.

31. The water resistant phosphate ceramic products of the process set forth in claims 20, 21 or 22 hereof wherein said products have a foamed structure.

32. The water resistant phosphate ceramic products of the process set forth in claims 20, 21 or 22 hereof wherein said products have an unfoamed structure.

33. The products according to claim 32 hereof wherein said products comprise a filler.

34. The process according to claims 20, 21, or 22 hereof wherein said reaction solution comprises a surfactant.

35. The process according to claims 20, 21, or 22 hereof wherein said mixture comprises fibrous reinforcing material.

36. The process according to claims 20, 21, or 22 hereof wherein said intermixed material comprises a foaming agent.

37. The process according to claims 20, 21 or 22 hereof wherein said intermixed material comprises a foaming agent which is a carbonate selected from the group consisting of MgCO3, CaCO3, ZnCO3 or Li2CO3.

38. The process according to claims 20, 21 or 22 hereof wherein said intermixed material comprises a foaming agent which is a fluorinated hydrocarbon having a boiling point lower than the temperature at which said intermixed material becomes rigid.

39. A process for manufacturing rigid, water resistant phosphate ceramic material, said process comprising the steps of:
preparing a metal oxide comprising from about 11 to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consisting of Al2O3, MgO, CaO or ZnO or the hydrates thereof, preparing a reaction solution comprising a portion of said metal oxide and from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75%
by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content, preparing a mixture comprising the remainder of said metal oxide and about 100 parts by weight of calcium silicate, proportionally intermixing said mixture with said reaction solution, and placing the resulting intermixed material in a desired configuration and allowing the components thereof to interact, the amount of metal oxide used to prepare the reaction solution being selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs.

40. A process according to claim 39 hereof comprising from about 13 to about 26 parts of metal oxide, about 100 parts of calcium silicate, and from about 90 to about 150 parts of phosphoric acid solution comprising the equivalent of from about 40 to about 70 phosphorus pentoxide.

41. A process according to claim 39 hereof comprising from about 15 to about 22 parts of metal oxide, about 100 parts of calcium silicater and from about 100 to about 130 parts of phosphoric acid solution comprising the equivalent of from about 45 to about 65 phosphorus pentoxide.

42. The process according to claims 39, 40, or 41 hereof wherein the particle size of said metal oxide is not larger than 325 mesh (Tyler Standard) and the particle size of said calcium silicate is not larger than 200 mesh (Tyler Standard).

43. The process according to claims 39, 40, or 41 hereof wherein said metal oxide is aluminum oxide trihydrate.

44. The process according to claims 39, 40, or 41 hereof wherein said metal oxide is magnesium oxide.

45. The process according to claims 39, 40, or 41 hereof wherein said metal oxide comprises a mixture of aluminum oxide trihydrate and magnesium oxide.

46. The water resistant phosphate ceramic product of the process set forth in claims 39, 40, or 41 hereof.

47. The water resistant phosphate ceramic products of the process set forth in claims 39, 40 or 41 hereof wherein said products have a foamed structure.

48. The water resistant phosphate ceramic products of the process set forth in claims 39, 40 or 41 hereof wherein said products have an unfoamed structure.

49. The products according to claim 48 hereof wherein said products comprise a filler.

50. The process according to claims 39, 40, or 41 hereof wherein said reaction solution comprises a surfactant.

51. The process according to claims 39, 40, or 41 hereof wherein said mixture comprises fibrous reinforcing material.

52. The process according to claim 39, 40 or 41 hereof wherein said intermixed material comprises a foaming agent.

53. The process according to claims 39, 40 or 41 hereof wherein said intermixed material comprises a foaming agent which is a carbonate selected from the group consisting of MgCO3, CaCO3, ZnCO3, or Li2CO3.

54. The process according to claims 39, 40 or 41 hereof wherein said intermixed material comprises a foaming agent which is a fluorinated hydrocarbon having a boiling point lower than the temperature at which said intermixed material becomes rigid.

55. A composition suitable to provide a rigid, water-resistant phosphate ceramic material, said composition comprising:
from about 11 to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consisting of A12O3, MgO, CaO or ZnO or the hydrates 8 thereof;
from about 80 to about 190 parts by weight of phosphoric acid solution comprising the equivalent of from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content; and about 100 parts by weight of calcium silicate.

56. The invention according to claim 55 hereof wherein said composition comprises from about 13 to about 26 parts of metal oxide, about 100 parts of calcium silicate, and from about 90 to about 150 parts of phosphoric acid solution comprising the equivalent of from about 40 to about 70% phosphorus pentoxide.

57. The invention according to claim 55 hereof wherein said composition comprises about 15 to about 22 parts of metal oxide, about 100 parts of calcium silicate, and from about 100 to about 130 parts of phosphoric acid solution comprising the equivalent of from about 45 to about 65% phosphorus pentoxide.

58. The invention according to claims 55, 56 or 57 hereof wherein the particle size of said metal oxide is not larger than 325 mesh (Tyler Standard) and the particle size of said calcium silicate is not larger than 200 mesh (Tyler Standard).

59. The composition according to claims 55, 56 or 57 hereof wherein said metal oxide is aluminum oxide trihydrate.

60. The invention according to claims 55, 56 or 57 hereof wherein said metal oxide is magnesium oxide.

61. The invention according to claims 55, 56 or 57 hereof wherein said composition comprises a mixture of aluminum oxide trihydrate and magnesium oxide.

62. The invention according to claims 55, 56 or 57 hereof wherein said composition comprises a surfactant.

63. The invention according to claims 55, 56 or 57 hereof wherein said composition comprises a fibrous reinforcing material.

64. The invention according to claims 55, 56 or 57 hereof wherein said composition comprises a foaming agent.

65. The invention according to claims 55, 56 or 57 hereof wherein said composition comprises a foaming agent which is a carbonate selected from the group consisting of MgCO3, CaCO3, ZnCO3 or Li2CO3.

66. The invention according to claims 55, 56 or 57 hereof wherein said composition comprises a foaming agent which is a fluorinated hydrocarbon having a boiling point lower than the temperature at which said intermixed material becomes rigid.

67. A rigid, water-resistant phosphate ceramic material obtained by reacting (1) from about 11 to about 65 parts by weight calculated on an anhydrous basis of at least one metal oxide selected from the group consisting of Al2O3, MgO, CaO or ZnO or the hydrates thereof;
(2) from about 80 to about 190 parts by weight of a phosphoric acid solution comprising the equivalent of from about 35 to about 75% by weight of phosphorus pentoxide based on the weight of the acid solution, the water of hydration of said metal oxide being included when calculating the phosphorus pentoxide content; and (3) about 100 parts by weight of calcium silicate.

68. The invention according to claim 67 hereof comprising from about 13 to about 26 parts of metal oxide, about 100 parts of calcium silicate, and from about 90 to about 150 parts of phosphoric acid solution comprising the equivalent of from about 40 to about 70%
phosphorus pentoxide.

69. The invention according to claim 67 hereof comprising from about 15 to about 22 parts of metal oxide, about 100 parts of calcium silicate, and from about 100 to about 130 parts of phosphoric acid solution comprising the equivalent of from about 45 to about 65%
phosphorus pentoxide.

70. The invention as set forth in claims 67, 68 or 69 hereof wherein said ceramic material is obtained by reacting a reaction solution and a component mixture, said reaction solution comprising said phosphoric acid solution and at least a portion of said metal oxide, and said component mixture comprising said calcium silicate and the remainder of said metal oxide.

71. The invention according to claims 67, 68, or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs.

72. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein the particle size of said metal oxide is not larger than 325 mesh (Tylar Standard) and the particle size of said calcium silicate is not larger than 200 mesh (Tyler Standard).

73. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein said metal oxide is aluminum oxide trihydrate.

74. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein said metal oxide is magnesium oxide.

75. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein said metal oxide comprises a mixture of aluminum oxide trihydrate and magnesium oxide.

76. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein said ceramic material comprises a surfactant.

77. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein said ceramic comprises a fibrous reinforcing material.

78. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein said ceramic material comprises a foaming agent.

79. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approximately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein the composition comprises a foaming agent which is a carbonate selected from the group consisting of MgCO3, CaCO3, ZnCO3 or Li2CO3.

80. The invention according to claims 67, 68 or 69 hereof wherein the amount of metal oxide used to prepare said reaction solution and the temperature of said reaction solution are selected so as to approxi-mately predetermine the point in time at which said intermixed material becomes rigid relative to the point in time at which vaporization of the water occurs and wherein the composition comprises a foaming agent which is a fluorinated hydrocarbon having a boiling point lower than the temperature at which said intermixed material becomes rigid.