FR2520727A1 - PROCESS FOR FORMING VANADIUM OXIDE COATINGS ON GLASS SUPPORTS AND PRODUCTS OBTAINED - Google Patents

Abstract

A PROCESS FOR THE DEPOSITION OF VANADIUM OXIDE FILMS ON GLASS SUPPORTS, AS WELL AS A THERMOCHROMIC VO FILM FOR THE VARIABLE TRANSMITTANCE OF SOLAR ENERGY AND A CONDUCTIVE VO FILM, EVERY BOTH FORM CHEMICAL VAPOR, USING VANADIUM LIQUID COMPOUNDS. THERE IS ALSO MENTION OF DOPING THERMOCHROMIC VANADIUM OXIDE FILMS, TO REDUCE THE TRANSITION TEMPERATURE.

Description

The present invention relates generally to the glass technique

  coated with metal oxides and, more specifically, the

  glass technique coated with vanadium oxide.

  U.S. Patent No. 2,383,410,110 (Rozgonyi) discloses a process for the formation of thin films of V 02 which has

  tooth the essential transition from metal to semiconductor phase pre-

  felt by the monocrystalline form and which do not undergo al-

  repeated cycling through the transition In one of

  its embodiments, the method comprises the operations

  sistant to dissociate by crackling a cathode of V 205 in an inert atmosphere, in the presence of the desired substrate, to form an amorphous film of V Ox, x being greater than 1.5 but less than 2, then to weakly oxidize the film for the transform into VO 2 or strongly oxidize the film to transform it into V 205 which is then converted into V 203 by reduction As

  alternatively, a vanadium cathode can be dissociated by crackles-

  similarly in an inert atmosphere to form a polycrystalline vanadium film which is first

  oxidized to V 205, then transformed into V 203 by reduction.

  The present invention involves, for the formation of vanadium oxide films, the chemical dep 8 t in the vapor phase from a liquid organovanadian compound such as vanadium propylate Vanadium oxide films containing VO 2

  present a transition from one state to another, both electric and optical

  that at a nominal transition temperature of about 6820.

  A glass rev Otu of a vanadium oxide film containing V 02 according to the present invention can be used advantageously for the contr 8 passive solar energy, because it has an infrared transparency significantly lower in the metallic $ phase, compared to the infrared transparency of

  the semiconductor phase Vanadium oxide films con-

  holding Y 20 O are electrically conductive at room temperature, having a resistivity of less than 1000 ohms per 6.45 cm 2 for a film thickness having a light transparency of approximately 24 to 35% on transparent float glass 6 m thick Vanadium oxide films containing V 205 can also be prepared by chemical vapor deposition according to the present invention. These films can be

  then subjected to a reduction to form thermal films.

mochromics containing VO 2.

  The present invention also embraces the deposition of film-

  thermochromics containing VO 2 which have a range of temperatures

  transition from one state to another lower than the normal transition temperature, by around 6820 The lowering of the temperature range from state to transition results from doping

  V 02 film with other materials, such as

  laid niobium, molybdenum, iridium, tantalum or tungsten A glass coated with a film of vanadium oxide

  according to the present invention can be used in parti-

  particularly advantageous for passive energy control

  solar, because it has a clear infrared transparency

  lower in the conductive phase, compared to the infrared transparency of the semiconductor phase and that it has a transition temperature range from one state to another which is low enough for it to be able to be used in a large

  variety of climatic conditions.

  Fig 1 illustrates the transition from one optical state to another of a vanadium oxide film (VO 2) formed directly by

chemical vapor depft.

  Fig 2 illustrates the transition from a state of electrical resistance

  stick to the other which accompanies the transition from an optical state to

the other, illustrated in fig 1.

  Fig. 3 illustrates the passage from one optical state to another of a doped vanadium oxide film according to the present invention, by comparison of the transparency to solar energy of a sample of glass coated with the room temperature with

  the transparency of the heated sample above its temperature

transitional structure.

  FIG. 4 shows the transition temperature range of a doped vanadium oxide film according to the present invention,

  by a representation of the resistance as a function of the temperature

  ture. Numerous coatings of metals and / or metal oxides are known which can be advantageously used for the control of solar energy Typically, such coatings reflect a high proportion of the incident solar energy, in order to minimize the heat gain inside a structure, while allowing sufficient transmission

  of the visible part of the spectrum for lighting the interior space

  tieur It would be particularly desirable, in architecture, to have, for the passive control of solar energy, a window with variable transmittance which would lower to a minimum the transmission in summer, when the temperature is high and that

  the incident solar energy reaches a maximum, but which transmits

  solar energy when the temperature is low La

  variable transmittance in a window can be obtained by photo-

  chromism, giving rise to darkening in response to the ray-

  solar ultraviolet light, typically using halogens

  silver nures But the absorption by the glass of solar radiation over the entire spectrum leads to heating and bleaching which alter the photochromic properties

  of glass The present invention achieves transmittance varia-

  ble by means of a thermochromic reaction, consequence of a transition from one optical state to another when an oxide film

  of vanadium is heated by absorbed solar energy.

  Vanadium oxide (VO 2) undergoes a phase transition, from the monoclinic crystallographic class to the tetragonal class, at a nominal temperature of 689 C. This phase transition is accompanied by a rapid passage, with regard to the electrical resistivity, from a semiconductor behavior to a metallic behavior, the change in resistivity being approximately 103 to 105 times in a single crystal In addition to passing from one state of electroconduction to another, a vanadium oxide film (VO 2) also undergoes a transition from one optical state to another markedly different in the infrared region of the spectrum, as shown in Figs 1 and 2, as well as, to a small extent, a transition from: my state optic to another in the spectral region of

visible light.

  Vanadium oxide films are prepared, according to the present invention, by chemical vapor deposition from organovanadian compounds, such as liquid vanadium i-propylate and vanadium n-propylate. be used as thermochromic glass for passive solar energy control, the vanadium oxide coating must have a

  wide variation of optical state in the infrared range of the spec-

  be solar, a temperature range, for this transition from a state

  to the other, which is correlated with the actual temperatures

  ves reached by a window exposed to solar radiation, and appropriate properties of passage from one state to another with

  a film thickness that is thin enough to avoid iridescence

  Preferably, the film thicknesses are between approximately 10 and 150 nm. These properties can be offered by vanadium oxide films prepared according to the present invention. To prepare thin films of vanadium oxide on glass supports by chemical vapor deposition, it is possible to

  use a variety of organovanadian compounds, preferably

  rence those which are in liquid form under ordinary conditions

  temperature and pressure float soda glass

  lime-silica and borosilicate glass can be used

  as supports The glass supports are preheated, typical-

  at a temperature of at least approximately 35020, in a conventional tubular oven, open at its two ends for the entry and exit of the supports. A pneumatically controlled pusher arm can be used to bring a substrate into the zone of

  heating, take it out and place it on a conveyor belt

  which leads it to a DCV coating chamber (deposit

  chemical vapor phase), located below an exhaust hood

  The DCV coating chamber contains an organovanadian compound, such as vanadium i-propylate or liquid vanadium n-propylate, which is heated to a temperature high enough to be vaporized The vapors of Anovanadian org compound are entrained in a gas stream towards the heated support,

  on which it is pyrolyzed to form vanadium oxide.

  In a preferred embodiment of the present invention,

  vanadium i-propylate is vaporized and entrained in a cou-

  of non-oxidizing gas, such as nitrogen or a molding gas,

  towards a heated glass support An oxy-

  of vanadium on the glass which then passes through a tunnel

  run by a stream of molding gas, to an annealing oven o the coated glass is cooled to room temperature When the VO 2 is formed from vanadium i-propyrlate, the glass coated with vanadium oxide which results is semiconductor at room temperature, with a solar infrared transmittance which is greater than about 30% at wavelengths between 0.8 and 2.2 microns, while above the

  transition temperature, 68 ° C nominally, the film

  holding VO 2 is typically conductive and has a total solar infrared transmittance less than

% about.

  To promote the optical response of a vanadium oxide film, it may be appropriate to fill the glass surface with a primary bonding layer focusing the chemical deposition

  vapor phase of the vanadium oxide coating The best

  bonding che can be obtained with a coating of tin oxide, typically from 70 to 80 nm thick The bonding coating with tin oxide is preferably formed by deposition

  pyrolytic of an organostannous compound Bioxy-dandruff

  of silicon and titanium are also suitable as primary bonding layers The use of such bonding films, especially of 8 N 02, seems to promote the crystallinity and the formation of V 02 rather than 8 t than other vanadium oxides , which results in a film rich in V 02 which has very good properties for passing from one optical state to another. The transition properties of the vanadium oxide coating from one optical state to the other are determined by scanning in the transmittance mode with a Cary 14 spectrophotometer (comparable spectrophotometers are now offered by Varian Associates) over the entire range of the spectral range of

  0.8 to 2.2 microns The sample of glass coated with vanilla oxide

  dium is maintained in an insulated support, provided with a passage opening of the beam Two cylindrical heating elements of 25

  watts, in contact with the edges of the glass just outside the

  beam passage vertex, used to heat the sample of glass coated with vanadium oxide over the whole range of the temperature range from state to state

  spectral is performed before and after heating, without displacement

  Sample results Typical results are given on

fig 1 and 2.

  The temperature range from the transition from an optical state to the

  tre is determined in a separate experiment, which also gives

  a measure of the transition from one state of thermoresistivity to another.

  The flat head probe of an Omega Amprobe R Fastemp temperature measurement device (offered by Omega Engineering, Inc, Stanford, Connecticut) is stapled flush with a narrow strip of

  the surface of the vanadium oxide film Immediate proximity

  diate on both sides of the sample are clamps

  crocodile, connected to an ohmmeter for resistance measurement.

  The resistance is measured as a function of the temperature, while the sample is heated over the entire range of

  transition temperature A sample measurement is shown

felt in fig 3.

  In general, it seems that, on the possibility of variation of 103 to 105 times of the thermoresistivity of the oxide of? vanadium (V 02), a variation in thermoresistivity of the order

  of about 2 times is sufficient to ensure optimum variation

  that having the magnitude required for passive control of solar energy in the spectral range of 0.8 to 2.2 microns The temperature range for the transition from one optical state to another, around the nominal 689 C typical of relatively pure single crystals of vanadium oxide (V 02), is close to the range of 45 to 6020 approximately which is effectively reached in the windows exposed to the south during the summer I 1 also appears that the passage properties of one optical state to another can be obtained with vanadium oxide films sufficiently thin to avoid

visible iridescence.

  V 02 films with lowered temperatures

  from one state to another are prepared, according to the present

  te invention, by doping with oxides of niobium, molybdenum, iridium, tantalum or tungsten, these metal cations having an ionic radius larger than that of vanadium In one embodiment of the present invention, carriers glass are immersed in a solution composed of 1 part by volume of vanadium i-propylate, 3 parts by volume of 2-propanol

  and about 2.5 to 4 g per liter of W O C O 14 at room temperature.

  The film is formed by hydrolysis in ambient air. The coated glass is then heated, preferably in a reducing atmosphere, and in particular in an atmosphere of molding gas containing an aromatic hydrocarbon, at a temperature

  sufficient and for a sufficient time to form a film

  thermochromic cule of V 02 which passes from one state to another in a temperature range situated above ambient temperature, but below the 6820 C characteristics The film of VO 2 is semiconductor at ambient temperatures, with transmittance total solar infrared that appears on the

  fig 3, while above the transition temperature range

  tion, the film containing V 02 is characteristically conductive

  teristic and has a solar infrared transmittance which is

  less than about 10%, as shown in fig 4.

  A greater variation in thermoresistivity can be obtained by using liquid vanadium i-propylate entrained in nitrogen gas, to form highly oxidized vanadium oxide (V 205) on a glass surface heated to monk at around 3009 C. The glass coated with vanadium oxide passes into. a tunnel traversed by a stream of air, towards an annealing oven also traversed by a stream of air, in which the coated glass is cooled to ambient temperature The coating

  resulting vanadium oxide is made primarily of V 205.

  To obtain the thermochromic VO 2, the coating of vanadium oxide is reduced in a reducing atmosphere, preferably a molding gas atmosphere containing a small proportion of aromatic hydrocarbon, at a temperature of the order of 325 to

  4752 C The thermochromic V 02 film formed in this way

  re is semiconductor at room temperature, with the trans-

  mittance of the solar infrared represented in fig 2, tan-

  say that above the transition temperature, the film of

  V 2 is typically conductive, with a transmit-

  total solar infrared tance of less than about 10%.

  The variation in thermoresistivity is approximately 1000 times, as

shown in fig 3.

  Thin conductive films of vanadium oxide containing V 203 can be formed by chemical vapor deposition using vanadium npropylate Glass carriers are

  preheated, typically at a temperature of at least 450 O

  in a conventional tubular oven, open at its two ends

  mites for the entry and exit of the supports Liquid vanadium n-propylate is vaporized and entrained in a stream of nitrogen

  gaseous to the heated support, on which the organovana-

  dien is pyrolyzed to form vanadium oxide The glass coated with vanadium oxide passes through a tunnel traversed by a current of molding gas, towards an annealing furnace also traversed by a current of molding gas, in which glass

  rev tu is cooled to room temperature The film con-

  conductive of V 20 resulting is typically transparent in gray, as opposed to the color from yellow to brown presented by VO 2, and it typically has a resistance of the order of 200 to 300 ohms per 6.45 cm 2 of preferably

  film thicknesses are between 20 and 150 nm.

  The present invention will be better understood using examples

  special ples whose description follows.

Example I

  A glass support is heated to a temperature of about 6352 C and brought into contact with a solution composed of 2 parts by volume of dibutyltin diacetate and 1 part by volume of methanol A coating of tin oxide '' about 70 to 80 nm thick is formed on the surface of the glass Glass, lined with the bonding layer of tin oxide, passes through a

  chemical vapor deposition chamber 8 t, containing i-pro-

  liquid vanadium pylate which is heated to 127 ° C. for its vapor

  The vapors of organovanadian compound are entrained by nitrogen on the moving glass support which is at a temperature of approximately 5302 C. The vanadium oxide film formed on the glass support is yellow in transparency under fluorescent light The vanadium oxide film present

  a transition in the temperature range from 55 to 75 O approximately.

  The electrical variation of this film ranges from approximately 13,000 ohms at room temperature to approximately 5000 ohms above

  the transition temperature range This variation is accompanied by

  hne from a transition from one optical state to another, as shown

in fig 1.

Example II

  Vanadium i-propylate is heated to 127-0 in a chemical vapor deposition chamber 8 t The vapors of the organovanadian compound are entrained in a stream of nitrogen to a moving glass support, preheated to a temperature of around 4009 C, in order to deposit a film of vanadium oxide

  on the glass support not lined with a primary layer of additive

  The coated glass is cooled to room temperature in

  air, which results in a composition of vanadium oxide

  taking V 20 The film of V 205 is reduced to V 02 thermochro-

  mique by heating at a temperature of the order of 450 to 46320 for approximately 23 minutes, in an atmosphere of molding gas containing an aromatic hydrocarbon (obtained by heating to 1609 C a bath of Califux TT, machining oil produced by Witco Chemical Corp, Los Angeles, California) The V 02 film has an electrical variation between more than 105 ohms at room temperature and approximately 500 to 800 ohms above 682 C 0, with an optical variation of less than 10% transmittance of solar radiation between 0.8 and 2.2 microns, as shown in the

fig 2.

Example III

  Vanadium n-propylate is heated to 12720 to form vapors which are entrained in a stream of nitrogen to a moving glass support, preheated to a temperature of about 530 QO A conductive film of vanadium oxide ( V 203) is formed on the glass support The coated glass is cooled in an atmosphere of molding gas The film

  of vanadium oxide is gray in transparency under fluorescent light

  resc ente and it presents, at room temperature, a resistance

  tance of about 150 to 190 ohms per square inch at a thickness

  which allows a light transmittance of around 24%.

  Example IV A transparent sheet of float glass is immersed in

  * 25 a solution composed of 1 part by volume of vanilla i-propylate

  dium, 3 parts by volume of 2-propanol and approximately 4 g / 1 l of WOC 14, at room temperature The glass is extracted from the bath and hydrolysis takes place in the ambient air, to form a transparent film, yellow in transparency The coated glass is then heated to 3759 C in an atmosphere of molding gas For a period of one minute, the coated glass is exposed to hydrocarbon vapors entrained in a current of molding gas The hydrocarbon vapors Bont obtained by heating to 16020 a bath of Califlux TT, machining oil produced by Witco Chemical Corp, Los Angeles, California The glass coated with vanadium oxide thus obtained shows the transition from one optical state to another which is shown in fig 3 and it has the transition temperature

shown in fig 4.

  The above examples are given to illustrate the present invention. Various other supports, such as borosilicate glass, can also be used in production.

  vanadium oxide films according to the present invention.

  It is also possible to use other organovanadian compounds, such as vanardium ethylate, vanadium butylate, as well as vanadium chloride, VO 013 The reduction of V 205 after dep St can be avoided by incorporating a reducing agent, such as an aromatic hydrocarbon, in the atmosphere of the chamber during dep 8 t Other dopants, such as compounds of niobium, molybdenum, iridium and tantalum, as well as other compounds of tungsten, can also be used The deposition process

  chemical vapor phase of the present invention is particularly

  very interesting for coating-a glass ribbon in soft-

  In particular, in a process for the continuous production of float ice. Advantageous methods and devices for chemical vapor deposition are described in US Pat. Nos. 2,350,679 and 3,951,100 Various atmospheres can

  be used: oxidizing atmospheres such as air, atros-

  inert spheres such as nitrogen or argon, and reducing atmospheres such as molding gas or other mixtures of inert gases and reducing agents Other coating methods,

  especially vacuum deposition, can be applied

  Thermochromic V 02 cells are preferably used in multi-glazed window assemblies for the control of

  solar energy by variable transmittance of infrared radiation

  red A preferred form of multiple glazing assembly is described in US Patent No. 2,919,023

Claims (30)

  1 Process for the chemical vapor deposition of films   vanadium oxide, characterized in that it comprises the operations-   the steps of heating a glass support to a temperature sufficient to convert a vanadium compound to vanadium oxide, vaporizing a liquid vanadium compound, and contacting a surface of the heated glass support with the vapor of the vanadium compound , to deposit a film of oxide of vanadium on the surface of the glass.   2 Method according to claim 1, characterized in that the   vanadium compound is vanadium i-propylate.   3 Method according to claim 1, characterized in that the glass support is coated with a primary bonding layer, made of a material chosen from the group consisting of tin, silicon and titanium oxides, before 8 t chemical dep   in the vapor phase of vanadium oxide.   4 Method according to claim 3, characterized in that the vaporized vanadium i-propylate is brought into contact with the surface of the glass in a non-oxidizing atmosphere and that it is   formed a thermochromic film containing V 02.   Process according to claim 2, characterized in that the vanadium compound and the glass support are exposed to a   oxidizing atmosphere and in that a film is formed nant V 205.   6 Method according to claim 5, characterized in that the   glass coated with V 205 is then exposed to a reduced atmosphere   to reduce V 205 to VO 2.   7 Method according to claim 1, characterized in that the   organovanadian compound is vanadium n-propylate.   8 Method according to claim 7, characterized in that the glass coated with vanadium oxide is exposed to a non-oxidizing atmosphere and in that a conductive film of electricity containing V 203.   9 Method according to claim 1, characterized in that the vanadium oxide film is deposited with a thickness of at 150 nm.   Product prepared before the process of claim 1.   11 Product prepared according to the process of claim 4.   12 Product prepared according to the process of claim 5.   13 Product prepared according to the process of claim 8.   14 Product prepared according to the method of claim 9.   l 5 A method for depositing a film of vanadium oxide, characterized in that it comprises the operations consisting in heating a glass support to a temperature of at least approximately 3502 C, in vaporizing i vanadium propylate, to entrain the vanadium i-propylate vaporized in a stream of non-oxidizing gas towards the support, to bring a heated glass support surface into contact with the vanadium i-propylate vaporized in a   non-oxidizing atmosphere, to deposit a coat on this surface   vanadium oxide formula, and to cool the glass coated with oxy-   of vanadium in a reducing gas atmosphere, in order to obtain a thermochromic film containing VO 2   16 Product prepared according to the process of claim 15.   7 A method for depositing a film of vanadium oxide, characterized in that it comprises the operations consisting in heating a glass support to a temperature of at least about 300 ° C., in vaporizing vanadium i-propylate, entraining the vanadium i-propylate vaporized in a stream of inert gas to the support, contacting a surface of the support with the vanadium i-propylate vaporized to form a film of vanadium oxide, and cooling glass coated with oxide of   vanadium in air, to obtain a film containing V 205.   18 Method according to claim 17, characterized in that the V 205 is converted by reduction to VO 2 in a reducing atmosphere. Method according to claim 18, characterized in that   the reducing atmosphere is made of molding or machining gas.   Process according to Claim 19, characterized in that the reducing atmosphere also contains an aromatic hydrocarbon.   1 Product prepared according to the method of claim 20.   22 Process for the production of a coated glass product   conductive, characterized in that it comprises the operations consisting of heating a glass support to a temperature of at least about 400 QC, vaporizing vanadium n-propylate, entraining the vaporized vanadium npropylate towards the support   in a stream of nitrogen, to contact a surface of the sup-   wearing of glass heated with vanadium n-propylate vaporized to deposit on this surface a film containing V 203, and   cooling the coated glass product in an insufficient atmosphere   strongly oxidizing to convert V 203 to VO 2.   Method according to claim 22, characterized in that the   glass coated with V 20 is cooled in molding or working gas swim.   24 The method of claim 22, characterized in that the film containing V O is deposited with a thickness of about 150 nm and has a resistivity less than 1000 ohms per square inch.   25 Manufactured product, prepared according to the process of the claim cation 24.   26 Product for variable transmittance of solar radiation   re, characterized in that it comprises a glass support and a coating containing VO characterized by a = change from one optical state to another in the temperature range from 25 to 752 C 0, so that the total transmittance of solar energy in the infrared region decreases by a factor of at least 2 when the coating is heated over the whole range of transition temperature.   27 Product according to claim 26, characterized in that the coating containing a vanadium oxide has a thickness of at 150 nm.   28 Product according to claim 27, characterized in that the   total transmittance of solar energy at room temperature   te in the spectral region between 0.8 and 2.2 microns is greater than 30%, while the total transmittance of the solar energy of the product, at a temperature higher than the temperature   transition, is less than 15%.   29 Product according to claim 28, characterized in that the coating of thermochromic VO 2 is present on an interior surface of a glass support in a window structure with multiple glazing.   Process for the manufacture of a thermochromic pane, characterized in that it comprises the operations consisting in heating a glass support to a temperature sufficient to convert the vanadium n-propylate to vanadium oxide, in vaporizing n-propylate vanadium, to enter Iner n-propylate   of vanadium vaporized towards the support, in a sufficient atmosphere   strongly oxidizing to form a thermochromic film made of VO 2, but insufficiently oxidizing to form a film which is not thermochromic as a consequence of the proportion of V 205, and to bring into contact a surface of the glass support -heated with steam vanadium npropylate, in said oxidizing atmosphere, to deposit a film on this surface containing V 02.   31 Method according to claim 30, characterized in that the glass support is heated to a temperature of at least 4000 C and in that said atmosphere is made of a mixture of inert gas and oxygen l 32 Method according to claim 31, characterized in that the glass support is heated to a temperature of at least 500-0   and in that said atmosphere is made of a mixture of nitrogen and-   oxygen. 33 Method according to claim 32, characterized in that said atmosphere is made of 90% by volume of nitrogen and 10% by volume of oxygen.   4 Method according to claim 30, characterized in that the film containing V 02 is deposited with a thickness of approximately at 150 num.   35 Manufactured product, prepared according to the resale process indication 30.   j 6 Manufactured product, prepared according to the resale process dication 33.   Manufactured product, prepared according to the resale process cation 34.   38 In a process for manufacturing a thermochromic pane   that comprising the steps of contacting a surface of a glass support with a vanadium compound and heating the glass support to a temperature sufficient to   obtain a vanadium oxide film formed of V 02, improvement   ration consisting in doping this film with a compound which   lowers the transition temperature from one state to another of the VO 2.   Method according to claim 38, characterized in that the dopant is a compound of a metal whose ionic radius is greater   larger than the ionic radius of vanadium.   Process according to Claim 39, characterized in that the compound which lowers the transition temperature from one state to the other of V 02 is chosen from compounds of niobium, tantalum, iridium and -tungsten.   41 Method according to claim 38, characterized in that the vanadium compound is chosen from the group consisting of vanadium n-propylate, vanadium ethylate, vanadium butylate, vanadium oxychloride and mixtures of these compounds. 42 Method according to claim 41, characterized in that the glass is brought into contact, at room temperature, with a   composition containing vanadium i-propylate and oxy-   tungsten chloride, to form a film which is strong-   heated to obtain a thermochromic film formed   of VO 2 and doped with tungsten.   4 d Manufactured product, prepared according to the resale process dication 3 B.   44 Manufactured product, prepared according to the resale process indication 42.