CA1091891A - Process for producing titanium carbide - Google Patents
Process for producing titanium carbideInfo
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- CA1091891A CA1091891A CA289,044A CA289044A CA1091891A CA 1091891 A CA1091891 A CA 1091891A CA 289044 A CA289044 A CA 289044A CA 1091891 A CA1091891 A CA 1091891A
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Abstract
ABSTRACT OF THE DISCLOSURE
A process for producing titanium carbide by reacting a titanium chloride such as titanium trichloride or titanium dichloride with a carbon source and a metal selected from the group consisting of aluminum, magnesium, sodium, calcium and aluminium titanium alloy is improved by molding the mixture of the raw materials to form a molded mixture having a bulk density of 1 to 5 g/m? preferably 1.5 to 3 g/m? and heating the molded mixture in an inert atmosphere.
A process for producing titanium carbide by reacting a titanium chloride such as titanium trichloride or titanium dichloride with a carbon source and a metal selected from the group consisting of aluminum, magnesium, sodium, calcium and aluminium titanium alloy is improved by molding the mixture of the raw materials to form a molded mixture having a bulk density of 1 to 5 g/m? preferably 1.5 to 3 g/m? and heating the molded mixture in an inert atmosphere.
Description
- ~091891 The present invention relates to a process for producing titanium carbide.
Titanium carbide has been used as super alloy and raw matexial for preparing ceramics toGls, thermet(atrademark) tools and powderymetallurgy andthe coatingof heatresistant equipment. In indu~t~ial operation, titanium carbide has been produced by reducing titanium dioxide with a carbon source. However, it has been difficult to prevent incorporation of a certain content of oxygen in the resulting titanium carbide.
1~ Even though stoichiometric amounts of raw materials are mixed in the production of titanium carbide, titanium carbide having a deficiency of carbon has been obtained. When an excess of carbon source is added so as to prevent the deficiency of carbon, a mixture of free carbon and titanium ca~bide having a deficiency of carbon has been obtained, and titanium carbide having high purity has not been obtained.
~he pr~cess ~or producing titanium carbide by reaating hydro-carbon with gas~ous titanium tetrachloride at a high temperature is known. This process is directed to obtain mainly titanium carbide for coating and it is not suitable for obtaining titanium carbide powder having a desired shape.
The inventors have discovered a process for producing titanium carbide having remarkably high purity by mixing a solid titanium chloride which issolid at atmospheric pressure, -such as titanium dichloride and titanium trichloride with a carbon source and a metal such as aluminium, magnesium, sodium, calcium or aluminium-titanium alloy and heating the powdery mixture.
The present invention provides a process for producing titanium carbide having high purity which can be easily produced with high processability.
,r - 1 --~ ~091891 ~ ccordiny to the pres~nt invention there is provided a proccss for producing titanium carbide by reactin~ a titaniurn chloride with a carbon source and a metal selected from the group consisting of aluminium, magnesium, sodium, calcium and aluminum-titanium alloy, an improvement which comprises molding the mixtùre of the raw materials to form a molded mixture having a bulk density of 1 to 5 g/mQ and heating the molded mixture in an inert atmosphere so as to cause the reaction in the molded mixture.
In accordance with the present invention a mixture of the raw materials for producing titanium carbide such as titanium chloride, a reducing compound such as aluminum and the carbon source is molded and the molded mixture heated in an inert atmosphere to cause reaction therebetween.
Suitable titanium chlorides used in the process of the pr~en~ lnv@ntion are the ~olid chlorides which are solid at the normal temperature under the atmospheric pressure, such as titanium dichloride and titanium trichloride. Suitable metals used as the reducing agent include aluminum, magnesium, sodium, calcium, or aluminum-titanium alloy. One or more metals can be used. When the titanium content of the aluminum-titanium alloy is high it is difficult to pulverize it and the reaction velocity for forming the carbide is disadvantageously lower.
- A suitable composition of the aluminum-titanium alloy contains .
62 to 80~ of Ti and 38 to 20 ~ of Al. The carbon sources used . in the process of the present invention include carbon black , and graphite. The titanium chloride, the metal as the reducing agent and the carbon source used in the process of the present invention may be present in stoichiometric amounts. These raw materials are preferably mixed in the reaction system under inert atmospheric pressure.
The present in~entionthus provides a process for molding ' ~091891 a mixture of the raw materials and then, reacting the molded mixture. The compression pressure for molding the mixture of the raw materials can be sufficient to impart enough strength of the molded mixture for handling the molded mixture. When the compression pressure for molding is higher, the bulk density of the molded mixture is increased. When the molded mixture having high bulk density is used, the amount of the molded mixture per the unit volume of the reactor is advantageously increased, and the crystalline growth in the case of sintering of titanium carbide, can be improved. In the X ray diffraction of the sintered product, it is clear that the relative strength is higher than that of the product prepared without molding the raw materials. The fact may be caused by higher degree of the sintering effect.
The compression pressure for molding the raw materials is u~ually in a ranye of 0.2 to 10 ton/cm , preferalby 0.5 to 4 ton/cm2. The bùlk d~nsity of the molded mixture is usually in a range of 1 to 5 g/m~. The relative bulk density can be considered as a ratio o the bulk density of the molded mixture to the highest bulk density of the same mixture compressed under ultimate pressure. The relative bulk density of the molded mixture is usually in a ranye of 1.0 to 0.25, preferably 0.98 to 0.5, especially 0.95 to 0.6. When the bulk density or the relative bulk density of the molded mixture is too low, the mechanical strength of the molded mixture is lower whereby the molded mixture crumbles in processing. When the reaction is carried out by using the molded mixture having low bulk density, the molded mixture crumbles the purity of the product is lowered and the yield of the product is also lowered. When the bulk density or the relative bulk density of the molded mixture is too high, the diffusion of the by-products in the reaction is not enough whereby the content of the by-products in the product before the heat-treatment for t}le growth of crystals of titanium carbide may be increased. Most of the by-products may be removed by the heat-treatment. The yield and purity of the product are excellent when the molded mixture having the aforesaid bulk density is used.
The molding operation is preferably carried out in an iner~ yas atmosphere such as argon, nitrogen, or carbon dioxide gas. The shape and size of the molded mixture are not critical.
The molded mixture can be in the form of pellets, granules including block, and spherical granules.
The size of the molded mixture can be decided depending upon the size and the shape of the reactor. Usually, the diameter and/or the thickness of the molded mixture is in a range of 0.5 to 200 mm. The reaction may be carried out in a batch system or a continuous system. When the size of the molded mixture is relatively large, the batch system and the semi-co~tinuous ~ystem are particularly preferable~ The process of the present invention can be carried out in a fluidized bed system. In the latter case, the size of the molded mixture is not critical.
The reactionis carried ou-t under fluidization, the molded mixture by an inert gas which may be recycled. Accordingly, the by-products can be easily separated and discharged from ; the reaction system with the recycling gas, and further, the amount of thé molded mixture per the unit volume of the reactor can be advantageously increased. When the reaction is carried out in a fixed bed system, similar results can be attained by . recycling the inert gas.
The reaction is carried out by heating the molded mixture in an inert gas atmosphere, such as argon and helium or in a vacuum. The temperature for the heating step is higher than the temperature for initiating the reaction of the raw materials in the molded mixtur~. When the reaction is carried out at too high a temperature, heat energy and raw material vaporization losses are disadvantageously caused. Accordingly, the temperature is preferably in a range of the temperature for ini,tiating the reaction in the molded mixture i.e. 700C
to 1300C.
The reaction product is usually further heat-treated by a conventional method so as to attain the growth of titanium carbide crystals. The titanium carbide treated by the heat-treatment is further treated by the pulverizing step, the washing step and the drying step etc. to produce the product.
In the process of the present invention, the shape of the molded mixture is substantially maintained after the reaction. Accordingly, the heat-treated product of the process of the present invention can be used without processing whereas it 1~ ne'ce~sary to mold the reacted product in the heat treatm~nt for the growth of titanium carbide crystals when the , ,,'; powdery mixture is used in the reaction without molding. When ~ the reaction is carried out using the powder form of the raw '' Z0 materials, the raw materials are scattered with entrainment with ' the by-product of met,al chloride, such as aluminum chloride ~when ' aluminum is used as the reducing agent), and the yield is - lowered.
In accordance with 'the reaction in the molded mixture ~,, of the raw materials, scattering of the raw materials are not ' caused and the yield is increased and the purity of the product ',' of the titanium carbide is higher than those of the product '; produced by reacting the powdery mixture without molding. The blank density is increased by molding the mixture of the raw . , materials whereby the amount of the treated materials per the unit volume of the reactor is increased. The reaction in the , molded mixture maintained in an inert atmosphere is remarkably :
~09189~
advantageous to perform the reaction for formin~ titanium carbide~
The present invention will be illustrated by the following Examples.
Example 1:
In a glove box purged with argon, 900 g of titanium trichloride (containing 22.4 ~ of aluminum trichloride), 121.7 g of aluminum and 51.09 g of carbon were mixed. The mixture was filled in a mold and was press-molded under the pressure of
Titanium carbide has been used as super alloy and raw matexial for preparing ceramics toGls, thermet(atrademark) tools and powderymetallurgy andthe coatingof heatresistant equipment. In indu~t~ial operation, titanium carbide has been produced by reducing titanium dioxide with a carbon source. However, it has been difficult to prevent incorporation of a certain content of oxygen in the resulting titanium carbide.
1~ Even though stoichiometric amounts of raw materials are mixed in the production of titanium carbide, titanium carbide having a deficiency of carbon has been obtained. When an excess of carbon source is added so as to prevent the deficiency of carbon, a mixture of free carbon and titanium ca~bide having a deficiency of carbon has been obtained, and titanium carbide having high purity has not been obtained.
~he pr~cess ~or producing titanium carbide by reaating hydro-carbon with gas~ous titanium tetrachloride at a high temperature is known. This process is directed to obtain mainly titanium carbide for coating and it is not suitable for obtaining titanium carbide powder having a desired shape.
The inventors have discovered a process for producing titanium carbide having remarkably high purity by mixing a solid titanium chloride which issolid at atmospheric pressure, -such as titanium dichloride and titanium trichloride with a carbon source and a metal such as aluminium, magnesium, sodium, calcium or aluminium-titanium alloy and heating the powdery mixture.
The present invention provides a process for producing titanium carbide having high purity which can be easily produced with high processability.
,r - 1 --~ ~091891 ~ ccordiny to the pres~nt invention there is provided a proccss for producing titanium carbide by reactin~ a titaniurn chloride with a carbon source and a metal selected from the group consisting of aluminium, magnesium, sodium, calcium and aluminum-titanium alloy, an improvement which comprises molding the mixtùre of the raw materials to form a molded mixture having a bulk density of 1 to 5 g/mQ and heating the molded mixture in an inert atmosphere so as to cause the reaction in the molded mixture.
In accordance with the present invention a mixture of the raw materials for producing titanium carbide such as titanium chloride, a reducing compound such as aluminum and the carbon source is molded and the molded mixture heated in an inert atmosphere to cause reaction therebetween.
Suitable titanium chlorides used in the process of the pr~en~ lnv@ntion are the ~olid chlorides which are solid at the normal temperature under the atmospheric pressure, such as titanium dichloride and titanium trichloride. Suitable metals used as the reducing agent include aluminum, magnesium, sodium, calcium, or aluminum-titanium alloy. One or more metals can be used. When the titanium content of the aluminum-titanium alloy is high it is difficult to pulverize it and the reaction velocity for forming the carbide is disadvantageously lower.
- A suitable composition of the aluminum-titanium alloy contains .
62 to 80~ of Ti and 38 to 20 ~ of Al. The carbon sources used . in the process of the present invention include carbon black , and graphite. The titanium chloride, the metal as the reducing agent and the carbon source used in the process of the present invention may be present in stoichiometric amounts. These raw materials are preferably mixed in the reaction system under inert atmospheric pressure.
The present in~entionthus provides a process for molding ' ~091891 a mixture of the raw materials and then, reacting the molded mixture. The compression pressure for molding the mixture of the raw materials can be sufficient to impart enough strength of the molded mixture for handling the molded mixture. When the compression pressure for molding is higher, the bulk density of the molded mixture is increased. When the molded mixture having high bulk density is used, the amount of the molded mixture per the unit volume of the reactor is advantageously increased, and the crystalline growth in the case of sintering of titanium carbide, can be improved. In the X ray diffraction of the sintered product, it is clear that the relative strength is higher than that of the product prepared without molding the raw materials. The fact may be caused by higher degree of the sintering effect.
The compression pressure for molding the raw materials is u~ually in a ranye of 0.2 to 10 ton/cm , preferalby 0.5 to 4 ton/cm2. The bùlk d~nsity of the molded mixture is usually in a range of 1 to 5 g/m~. The relative bulk density can be considered as a ratio o the bulk density of the molded mixture to the highest bulk density of the same mixture compressed under ultimate pressure. The relative bulk density of the molded mixture is usually in a ranye of 1.0 to 0.25, preferably 0.98 to 0.5, especially 0.95 to 0.6. When the bulk density or the relative bulk density of the molded mixture is too low, the mechanical strength of the molded mixture is lower whereby the molded mixture crumbles in processing. When the reaction is carried out by using the molded mixture having low bulk density, the molded mixture crumbles the purity of the product is lowered and the yield of the product is also lowered. When the bulk density or the relative bulk density of the molded mixture is too high, the diffusion of the by-products in the reaction is not enough whereby the content of the by-products in the product before the heat-treatment for t}le growth of crystals of titanium carbide may be increased. Most of the by-products may be removed by the heat-treatment. The yield and purity of the product are excellent when the molded mixture having the aforesaid bulk density is used.
The molding operation is preferably carried out in an iner~ yas atmosphere such as argon, nitrogen, or carbon dioxide gas. The shape and size of the molded mixture are not critical.
The molded mixture can be in the form of pellets, granules including block, and spherical granules.
The size of the molded mixture can be decided depending upon the size and the shape of the reactor. Usually, the diameter and/or the thickness of the molded mixture is in a range of 0.5 to 200 mm. The reaction may be carried out in a batch system or a continuous system. When the size of the molded mixture is relatively large, the batch system and the semi-co~tinuous ~ystem are particularly preferable~ The process of the present invention can be carried out in a fluidized bed system. In the latter case, the size of the molded mixture is not critical.
The reactionis carried ou-t under fluidization, the molded mixture by an inert gas which may be recycled. Accordingly, the by-products can be easily separated and discharged from ; the reaction system with the recycling gas, and further, the amount of thé molded mixture per the unit volume of the reactor can be advantageously increased. When the reaction is carried out in a fixed bed system, similar results can be attained by . recycling the inert gas.
The reaction is carried out by heating the molded mixture in an inert gas atmosphere, such as argon and helium or in a vacuum. The temperature for the heating step is higher than the temperature for initiating the reaction of the raw materials in the molded mixtur~. When the reaction is carried out at too high a temperature, heat energy and raw material vaporization losses are disadvantageously caused. Accordingly, the temperature is preferably in a range of the temperature for ini,tiating the reaction in the molded mixture i.e. 700C
to 1300C.
The reaction product is usually further heat-treated by a conventional method so as to attain the growth of titanium carbide crystals. The titanium carbide treated by the heat-treatment is further treated by the pulverizing step, the washing step and the drying step etc. to produce the product.
In the process of the present invention, the shape of the molded mixture is substantially maintained after the reaction. Accordingly, the heat-treated product of the process of the present invention can be used without processing whereas it 1~ ne'ce~sary to mold the reacted product in the heat treatm~nt for the growth of titanium carbide crystals when the , ,,'; powdery mixture is used in the reaction without molding. When ~ the reaction is carried out using the powder form of the raw '' Z0 materials, the raw materials are scattered with entrainment with ' the by-product of met,al chloride, such as aluminum chloride ~when ' aluminum is used as the reducing agent), and the yield is - lowered.
In accordance with 'the reaction in the molded mixture ~,, of the raw materials, scattering of the raw materials are not ' caused and the yield is increased and the purity of the product ',' of the titanium carbide is higher than those of the product '; produced by reacting the powdery mixture without molding. The blank density is increased by molding the mixture of the raw . , materials whereby the amount of the treated materials per the unit volume of the reactor is increased. The reaction in the , molded mixture maintained in an inert atmosphere is remarkably :
~09189~
advantageous to perform the reaction for formin~ titanium carbide~
The present invention will be illustrated by the following Examples.
Example 1:
In a glove box purged with argon, 900 g of titanium trichloride (containing 22.4 ~ of aluminum trichloride), 121.7 g of aluminum and 51.09 g of carbon were mixed. The mixture was filled in a mold and was press-molded under the pressure of
2 ton/cm2. The molded mixtùre was charged in a carbon crucible (24 cm x 10 cm x 8 cm) which was connected to a reaction system and was purged with argon. The reaction was carried out under an argon flow at 1000C for 1 hour.
In this case, the molded mixture had a diameter of 30 mm, a t thickness of 30 mm and a bulk density of 2.6 g/ml. The reactionproduct was further heated at 1500C for 1 hour under vacuum.
As the reference, the raw materials in powder form 'i were mlxed without molding and the reaction was carried out under the ~ame condltions and the reaction product was further heated at 1500C for 1 hour.
The results are shown in Table 1. When the raw materials were molded before the reaction, the yield was higher, and the ~itanium carbide having higher combined carbon content and lower oxygen content was obtained in comparlson with the case - reacting the powdery mixture. This was found by the chemical analysis.
~, .
. . .
"~
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',,' .
Table l:
. ~ .
Form of raw materials I Powder Molded product Yield (~) I 90 97 Chemial ana ~
Total carbon (%) 19.90 20.10 Free carbon (%) 0.15 0.10 Combined carbon (%) 19.75 20.00 :
Oxygen (~) 0.10 0.07 Iron component (%) 0.05> 0.05>
,, . _ Example 2:
In a glove box purged with argon, 664.9 g of titanium trichloride ~containing 22.6% of aluminum trichloride), 246.3 g o tit~nium-aluminum alloy (TiAl) and 80 g of carbon were mixed and the mixture was illed into a mold and was.press-molded under the pressure of 2 ton/cm2.. The molded mixture was charged in the carbon crucible of Example 1 which was connected to a reaction system and was purged with argon. The reaction was carried out under an argon flow at 1000C for 1 hour. In . .
this case, the molded mixture had a diameter of 30 mm, a thickness of 30 mm and a bulk density o-f 2.4 g/ml. The reaction product was further heated at 1500C for 1 hour in vacuum.
. As the reference, the raw materials in powder form were mixed without molding and the reaction was carried out under the same conditions and the reaction product was further `, heated at 1500C for 1 hour.
.:
, 30 The results are shown in Table 2. When the raw materials were molded before the reaction, the yield was higher than the case reactinq the powdery mixture.
~`
: - 7 -- 1091891 ~:
T ble 2:
Form of raw materials Powder Molded product _ .
Yield (~) 92 96 Chemical analysis Total carbon (%) 19. 80 20.00 Free carbon (~) 0.24 0.15 Combined carbon (~) 19.56 19.85 Oxygen (~) o. 20 0.10 Iron (%) 0.05> 0.05>
.
Example 3:
In a glove box purged with argon, 299 g of titanium ~richloirde (containing 22.6% of aluminum trichloride), 54.7 g of maynesium and 18 g of carbon were mixed. The mixture was fllled in a mold having a diameter of 30 mm, and was pre~s molded under the pressure o 4 ton/cm2. The molded mixture was charged in a carbon crucible which was connected to a reaction system, and was purged with argon. The reaction was carried out under an argon 1Ow at 1000C for 1 hour. In this case, the molded mixture had a bulk density of 2.S g/ml. The reaction !product was washed with water and dried and then, it was further - heated at 1500C for l hour in vacuum.
As the reference, the raw materials in powder form were mixed without molding and the reaction was carried out in the same condition and the reaction product was further heated at 1500C for 1 hour.
The results are shown in Table 3. When the raw materials were molded before the reaction, the yield was higher and the purity was higher than the case reacting the powdery mixture.
.~.' Table 3:
. ...... _ __ Form of raw materials Powder Molded product Yield (%) 90 95 -- . _ . . ...
Chemical analysis:
Total carbon (%) 20.00 20.10 Free carbon (%) 0.15 0.10 Combined carbon (~) 19.85 20.00 Oxygen (~) 0.15 0.07 Iron Component (%) 0.05> 0.05 .
Example 4:
~ In a glove box purged with argon, 892 g of titanium dichloride, 135 g of aluminum and 90 g of carbon were mixed.
The mixtur~ was filled into a mold having a diameter of 50 mm and was pr~s~-molded under th~ pressure of 4 ton/cm2. The molded mixture was charged in a carbon crucible which was connected to a reaction system and was purged with argon. The reaction was carried out under an argon flow at 1000C for 1 hour. In this case, the molded mixture had a bulk density of 2.4 g/ml. The reaction product was further heated at 1500C
~or 1 hour in vacuum.
As the reference, the raw materials in powder form were mixed without molding and the reaction was carried out under the same conditions and the reaction product was further heated at 1500C for 1 hour. The results are shown in Table 4.
When the raw materials were molded before the reaction, the yleld was higher than when reacting the powdery mixture.
.
, .
- g _ Table 4:
, Form of raw materials Powder ' Molded product .. . . . _ _ _ Yield ~) 91 j 97 - ---- . . _. _ Chemic_l anal~is:
Total carbon (~) 19.90 20.00 Free carbon (%) 0.05 0.05 Combined carbon (~) 19.85 l9.9S
10Oxygen (%) 0.10 0.05 Iron component (%) 0.05> 0.05 : - , . ..
Example 5:
; The mixture of the raw materials used in Example 1 was J; molded to form a molded mixture having a diameter of 5 mm, a thickn~s~ of 5 mm and a bulk density of 2.0 g/ml. In a fluidized reactor having an inner diameter of 50 mm, a height of 1000 mm and a perforated plate having many pores (1 mm 0 ), 450 g of the molded mixture was charged. Argon gas was fed from the bottom , ,, of the reactor at a rate of 10 to 20 liter/min., so as to main-tain a fluidizing condition and the inner part of the reactor .: . .
was heated to 1000C. Argon gas was discharged from the top ... .
, of the reactor and was recycled with collecting and separating the by-product of aluminum chloride in the recycling system at out of the reactor. After the reaction for 1 hour, the reaction product ~as heated at 1500C for 1 hour.
The results of the analysis of the reaction product are shown ~- in Table 5.
'.~ ' Table S:
. _ Yield (%) 97 .__ Chemical anal~sis:
Total carbon (~) 20.01 Free carbon (~) 0.07 Combined carbon (%) 19.94.
Oxygen (%) 0.10 Iron component (g) 0.05>
Example 6, In accordance with the process of Example 1 except using the molded mixture compressed under the pressure of 0.2 ton/cm2, the reaction and the heat-treatment were carried out.
The bulk density of the molded mixture was 1.2 g/m~.
The results are shown in Table 6.
Table 6 . 20 Form of raw materialsMolded mixture .
., .
Yield (%) 94 ,:, Chemical analysis:
. Total carbon (%) 19.85 . Free carbon (%) 0.15 :; . Combined carbon (%)19.70 Oxygen (%) 0.10 ; Iron component (%)0.05 : 30 Example 7:
: In accordance with the process of Example 1 except using the molded mixture compressed under the pressure of ~ lQ9189~
l0 ton/cm2 or 2 ton/cm2, the r~lction and the heat-treatment were carried out. The bulk densities of the molded ~ixtures were respectively 4 g/mQ and 2.6 g/mQ.
The contents of aluminum component and chlorine .
component in each molded mixture are as follows:
Table 7 .
I-- --- .
I Compressed 2 ¦ pressure (ton/cm ) 10 2 Bulk density (g/mQ) I 4 2.6 _ ' i Aluminum content (%) 2 3 ~ 0.3 Cblor ne content (~) 5-2 ! o-.
The results of chemical analy~is and yield of the products obtained by the reaction and the heat-treatment are as follows:
Table 8 ' .
,~ . ____ I .
" Compressed pressure 10 2 1' 20 (ton/cm2) _ _ , Bulk density (g/mQl 4 2.6 . ... .
: ! Yield ~) 95 97 . _ ........ ___ . .
. ~ . Chemical analysis: .
Total carbon (%)19.9020.10 : . Free carbon ~%)0.15 0.10 Combined carbon (~)19.75 20.00 : Oxygen (~) 0.10 0.07 . Iron component (%) 0.05> 0.05> i ,' . . .
.. ;~ .
In this case, the molded mixture had a diameter of 30 mm, a t thickness of 30 mm and a bulk density of 2.6 g/ml. The reactionproduct was further heated at 1500C for 1 hour under vacuum.
As the reference, the raw materials in powder form 'i were mlxed without molding and the reaction was carried out under the ~ame condltions and the reaction product was further heated at 1500C for 1 hour.
The results are shown in Table 1. When the raw materials were molded before the reaction, the yield was higher, and the ~itanium carbide having higher combined carbon content and lower oxygen content was obtained in comparlson with the case - reacting the powdery mixture. This was found by the chemical analysis.
~, .
. . .
"~
~:.
',,' .
Table l:
. ~ .
Form of raw materials I Powder Molded product Yield (~) I 90 97 Chemial ana ~
Total carbon (%) 19.90 20.10 Free carbon (%) 0.15 0.10 Combined carbon (%) 19.75 20.00 :
Oxygen (~) 0.10 0.07 Iron component (%) 0.05> 0.05>
,, . _ Example 2:
In a glove box purged with argon, 664.9 g of titanium trichloride ~containing 22.6% of aluminum trichloride), 246.3 g o tit~nium-aluminum alloy (TiAl) and 80 g of carbon were mixed and the mixture was illed into a mold and was.press-molded under the pressure of 2 ton/cm2.. The molded mixture was charged in the carbon crucible of Example 1 which was connected to a reaction system and was purged with argon. The reaction was carried out under an argon flow at 1000C for 1 hour. In . .
this case, the molded mixture had a diameter of 30 mm, a thickness of 30 mm and a bulk density o-f 2.4 g/ml. The reaction product was further heated at 1500C for 1 hour in vacuum.
. As the reference, the raw materials in powder form were mixed without molding and the reaction was carried out under the same conditions and the reaction product was further `, heated at 1500C for 1 hour.
.:
, 30 The results are shown in Table 2. When the raw materials were molded before the reaction, the yield was higher than the case reactinq the powdery mixture.
~`
: - 7 -- 1091891 ~:
T ble 2:
Form of raw materials Powder Molded product _ .
Yield (~) 92 96 Chemical analysis Total carbon (%) 19. 80 20.00 Free carbon (~) 0.24 0.15 Combined carbon (~) 19.56 19.85 Oxygen (~) o. 20 0.10 Iron (%) 0.05> 0.05>
.
Example 3:
In a glove box purged with argon, 299 g of titanium ~richloirde (containing 22.6% of aluminum trichloride), 54.7 g of maynesium and 18 g of carbon were mixed. The mixture was fllled in a mold having a diameter of 30 mm, and was pre~s molded under the pressure o 4 ton/cm2. The molded mixture was charged in a carbon crucible which was connected to a reaction system, and was purged with argon. The reaction was carried out under an argon 1Ow at 1000C for 1 hour. In this case, the molded mixture had a bulk density of 2.S g/ml. The reaction !product was washed with water and dried and then, it was further - heated at 1500C for l hour in vacuum.
As the reference, the raw materials in powder form were mixed without molding and the reaction was carried out in the same condition and the reaction product was further heated at 1500C for 1 hour.
The results are shown in Table 3. When the raw materials were molded before the reaction, the yield was higher and the purity was higher than the case reacting the powdery mixture.
.~.' Table 3:
. ...... _ __ Form of raw materials Powder Molded product Yield (%) 90 95 -- . _ . . ...
Chemical analysis:
Total carbon (%) 20.00 20.10 Free carbon (%) 0.15 0.10 Combined carbon (~) 19.85 20.00 Oxygen (~) 0.15 0.07 Iron Component (%) 0.05> 0.05 .
Example 4:
~ In a glove box purged with argon, 892 g of titanium dichloride, 135 g of aluminum and 90 g of carbon were mixed.
The mixtur~ was filled into a mold having a diameter of 50 mm and was pr~s~-molded under th~ pressure of 4 ton/cm2. The molded mixture was charged in a carbon crucible which was connected to a reaction system and was purged with argon. The reaction was carried out under an argon flow at 1000C for 1 hour. In this case, the molded mixture had a bulk density of 2.4 g/ml. The reaction product was further heated at 1500C
~or 1 hour in vacuum.
As the reference, the raw materials in powder form were mixed without molding and the reaction was carried out under the same conditions and the reaction product was further heated at 1500C for 1 hour. The results are shown in Table 4.
When the raw materials were molded before the reaction, the yleld was higher than when reacting the powdery mixture.
.
, .
- g _ Table 4:
, Form of raw materials Powder ' Molded product .. . . . _ _ _ Yield ~) 91 j 97 - ---- . . _. _ Chemic_l anal~is:
Total carbon (~) 19.90 20.00 Free carbon (%) 0.05 0.05 Combined carbon (~) 19.85 l9.9S
10Oxygen (%) 0.10 0.05 Iron component (%) 0.05> 0.05 : - , . ..
Example 5:
; The mixture of the raw materials used in Example 1 was J; molded to form a molded mixture having a diameter of 5 mm, a thickn~s~ of 5 mm and a bulk density of 2.0 g/ml. In a fluidized reactor having an inner diameter of 50 mm, a height of 1000 mm and a perforated plate having many pores (1 mm 0 ), 450 g of the molded mixture was charged. Argon gas was fed from the bottom , ,, of the reactor at a rate of 10 to 20 liter/min., so as to main-tain a fluidizing condition and the inner part of the reactor .: . .
was heated to 1000C. Argon gas was discharged from the top ... .
, of the reactor and was recycled with collecting and separating the by-product of aluminum chloride in the recycling system at out of the reactor. After the reaction for 1 hour, the reaction product ~as heated at 1500C for 1 hour.
The results of the analysis of the reaction product are shown ~- in Table 5.
'.~ ' Table S:
. _ Yield (%) 97 .__ Chemical anal~sis:
Total carbon (~) 20.01 Free carbon (~) 0.07 Combined carbon (%) 19.94.
Oxygen (%) 0.10 Iron component (g) 0.05>
Example 6, In accordance with the process of Example 1 except using the molded mixture compressed under the pressure of 0.2 ton/cm2, the reaction and the heat-treatment were carried out.
The bulk density of the molded mixture was 1.2 g/m~.
The results are shown in Table 6.
Table 6 . 20 Form of raw materialsMolded mixture .
., .
Yield (%) 94 ,:, Chemical analysis:
. Total carbon (%) 19.85 . Free carbon (%) 0.15 :; . Combined carbon (%)19.70 Oxygen (%) 0.10 ; Iron component (%)0.05 : 30 Example 7:
: In accordance with the process of Example 1 except using the molded mixture compressed under the pressure of ~ lQ9189~
l0 ton/cm2 or 2 ton/cm2, the r~lction and the heat-treatment were carried out. The bulk densities of the molded ~ixtures were respectively 4 g/mQ and 2.6 g/mQ.
The contents of aluminum component and chlorine .
component in each molded mixture are as follows:
Table 7 .
I-- --- .
I Compressed 2 ¦ pressure (ton/cm ) 10 2 Bulk density (g/mQ) I 4 2.6 _ ' i Aluminum content (%) 2 3 ~ 0.3 Cblor ne content (~) 5-2 ! o-.
The results of chemical analy~is and yield of the products obtained by the reaction and the heat-treatment are as follows:
Table 8 ' .
,~ . ____ I .
" Compressed pressure 10 2 1' 20 (ton/cm2) _ _ , Bulk density (g/mQl 4 2.6 . ... .
: ! Yield ~) 95 97 . _ ........ ___ . .
. ~ . Chemical analysis: .
Total carbon (%)19.9020.10 : . Free carbon ~%)0.15 0.10 Combined carbon (~)19.75 20.00 : Oxygen (~) 0.10 0.07 . Iron component (%) 0.05> 0.05> i ,' . . .
.. ;~ .
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for producing titanium carbide by reacting a titanium chloride which is solid at normal temperature under normal atmospheric pressure with a carbon source and a metal selected from the group consisting of aluminum, magnesium, sodium, calcium and aluminum-titanium alloy, an improvement which com-prises molding the mixture of the raw materials to form a molded mixture having a bulk density of 1 to 5 g/m? and heating the molded mixture in an inert atmosphere so as to cause the reaction in the molded mixture.
2. A process according to Claim 1 wherein the molded mixture of the raw materials is heated in a fixed bed.
3. A process according to Claim 1 wherein the molded mixture of the raw materials is heated under fluidizing conditions in an inert atmosphere.
4. A process according to Claim 1, 2 or 3, wherein aluminum, titanium trichloride and the carbon source are mixed and molded and the molded mixture is heated in an inert gas.
5. A process according to Claim 1, 2 or 3, wherein the temperature for heating the molded mixture is in a range of 700 to 1300°C.
6. A process as claimed in claim 1, 2 or 3, in which the titanium chloride in titanium dichloride or titanium in trichloride.
7. A process as claimed in claim 1, 2 or 3, in which the aluminum-titanium alloy contains 62 - 80% Ti and 38% to 20%
Al.
Al.
8. A process as claimed in claim 1, 2 or 3, in which the carbon source is carbon black or graphite.
9. A process as claimed in claim 1, 2 or 3, in which the titanium chloride, carbon source and metal are used in stoichiometric amounts.
10. A process as claimed in claim 1, 2 or 3, in which the bulk density is from 1.5 to 3 g/ml.
11. A process as claimed in claim 1, 2 or 3, in which the mixture is molded at a compression pressure from 0.2 to 10 ton/cm2.
12. A process as claimed in claim 1, 2 or 3, in which the relative bulk density in molded mixture is 1.0 to 0.25.
13. A process as claimed in claim 1, 2 or 3, in which the relative bulk density in molded mixture is 0.98 to 0.5.
14. A process as claimed in claim 1, 2 or 3, in which the relative bulk density in molded mixture is 0.95 to 0.6
15. A process as claimed in claim 1, 2 or 3, in which the inert atmosphere is an inert gas atmosphere selected from argon, helium, nitrogen or carbon dioxide gas or is a vacuum.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP124830/1976 | 1976-10-20 | ||
| JP12483076A JPS5350762A (en) | 1976-10-20 | 1976-10-20 | Field effect type liquid crystal display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1091891A true CA1091891A (en) | 1980-12-23 |
Family
ID=14895142
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,044A Expired CA1091891A (en) | 1976-10-20 | 1977-10-19 | Process for producing titanium carbide |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5350762A (en) |
| CA (1) | CA1091891A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108408727A (en) * | 2018-03-09 | 2018-08-17 | 燕山大学 | A kind of synthesis of easily stripped ceramic material MAX phases and stripping means |
-
1976
- 1976-10-20 JP JP12483076A patent/JPS5350762A/en active Pending
-
1977
- 1977-10-19 CA CA289,044A patent/CA1091891A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108408727A (en) * | 2018-03-09 | 2018-08-17 | 燕山大学 | A kind of synthesis of easily stripped ceramic material MAX phases and stripping means |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5350762A (en) | 1978-05-09 |
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