Titanium diboride-graphite composites

Claim 2

A process for manufacturing a carbon-TiB 2 composite article comprising blending coke, a first carbonizable binder and a first TiB 2 forming reactant to form a dispersion, shaping said article, baking said article to carbonize said binder, impregnating said article under alternate cycles of vacuum and pressure at least once with a second TiB 2 -forming reactant in liquid form, and heating said article to a TiB 2 -forming temperature to form said carbon-TiB 2 composite article.

Claim 3

The process of claim 1 wherein the coke is a regular calcined petroleum coke having a mean particle diameter of approximately 3 mm.

Claim 4

The process of claim 1 wherein the binder is a molten coal tar pitch having a softening point from 100° to 120° C., used at a temperature of approximately 160° to 175°.

Claim 5

The process of claim 1 wherein the first TiB 2 -forming reactant is TiO 2 and the second TiB 2 -forming reactant comprises a boron compound selected from the group consisting of B 4 C, B 2 O 3 , H 3 BO 3 and Na 2 B 4 O 7 .10H 2 O.

Claim 6

The process of claim 1 wherein the second TiB 2 -forming reactant is a boron compound selected from the group consisting of B 4 C and B 2 O 3 , dispersed in a liquid selected from the group consisting of molten petroleum pitch and phenolic condensates.

Claim 7

The process of claim 1 wherein the second TiB 2 -forming reactant is molten B 2 O 3 , used at about 500° C.

Claim 8

The process of claim 1 wherein the second TiB 2 -forming reactant is B 2 O 3 , HBO 3 , or Na 2 B 4 O 7 .10H 2 O in water solution.

Claim 9

The process of claims 1 or 15 wherein the article is baked on a temperature cycle rising to 700° to 1100° C. over a period of 1 to 10 days.

Claim 10

The process of claims 1 or 15 wherein the article is impregnated with the second TiB 2 -forming reactant under alternate cycles of vacuum and a pressure of from 1.7×10 5 to 6.9×10 5 Pa (25 to 100 psi).

Claim 11

The process of claims 1 or 15 wherein the article after impregnation is baked on a cycle with the temperature rising to 700° to 1100° C. over a period of 1 to 10 days, then further heated to a TiB 2 -forming temperature of at least 1200° C.

Claim 12

The process of claims 1 or 15 wherein after heating to the TiB 2 -forming temperature the article is further heated to a temperature of at least 2200° C.

Claim 13

The process of claims 1 or 15 wherein the article after heating to the TiB 2 -forming temperature is cooled, then re-impregnated at least once under alternate cycles of vacuum and pressure with the second TiB 2 -forming reactant in liquid form, re-baked on a cycle rising to 700° to 1100° C. over a period of 1 to 10 days, and re-heated to the TiB 2 -forming temperature of at least 1200° C.

Claim 14

The process of claims 1 or 15 wherein the article after heating to the TiB 2 -forming temperature is impregnated with petroleum pitch under alternate cycles of vacuum and pressure at about 240° C. and 6.9×10 5 Pa, re-baked on a cycle rising to 700° to 1100° C. over a period of 1 to 10 days, and heated to at least 2200° C.

Claim 15

The process of claims 1 or 15 wherein the article is re-impregnated with a dispersion of both the first and second TiB 2 -forming reactants in petroleum pitch under alternate cycles of vacuum and pressure of 1.7 to 6.9×10 5 Pa at about 240° C., baked on a cycle rising to 700° to 1100° C. over a period of 1 to 10 days, heated to at least 2200° C. to form a TiB 2 -graphite composite.

Claim 16

The process of claim 1 wherein the first TiB 2 -forming reactant is a boron compound and the second TiB 2 -forming reactant is TiO 2 .

Claim 17

The process of claims 1 or 15 wherein the article is shaped by molding at a pressure of about 1.4×10 7 Pa.

Claim 18

The process of claims 1 or 15 wherein the article is shaped by extrusion.

Claim 19

A process of manufacturing a cathodic element for a Hall aluminum cell comprising dispersing a first TiB 2 -forming reactant selected from the group consisting of B 4 C, H 3 BO 3 , and B 2 O 3 and coke particles in molten coal tar pitch binder to form a plastic mass, shaping said mass to form said cathodic element, baking said element on a rising temperature cycle reaching 700° to 1100° C. over a period of 1 to 10 days, removing said element from said furnace, impregnating said element under a pressure of about 6.9×10 5 Pa with TiO 2 dispersed in molten petroleum pitch, re-baking said element to 700° to 1100° C. over a period of 1 to 10 days, heating said element to 1750° C. to form a carbon-TiB 2 composite, re-impregnating said element with said petroleum pitch at about 240° C. under about 6.9×10 5 Pa pressure, re-baking said element to 700° to 1100° C. over 1 to 10 days, and heating said element to 2250° C. in an argon atmosphere to form a graphite-TiB 2 composite cathodic element.

Claim 20

A process of manufacturing a cathodic element for a Hall aluminum cell comprising dispersing a first TiB 2 -forming reactant selected from the group consisting of B 4 C, H 3 BO 3 , and B 2 O 3 and coke particles in molten coal tar pitch binder to form a plastic mass, shaping said mass to form said cathodic element, baking said element on a rising temperature cycle reaching 700° to 1100° C. over a period of 1 to 10 days, removing said element from said furnace, impregnating said element under a pressure of about 6.9×10 5 Pa with TiO 2 dispersed in molten petroleum pitch, re-baking said element to 700° to 1100° C. over a period of 1 to 10 days, heating said element to 1750° C. to form a carbon-TiB 2 composite, re-impregnating said element with said petroleum pitch at about 240° C. under about 6.9×10 5 Pa pressure, re-baking said element to 700° to 1100° C. over 1 to 10 days, and heating said element to 2250° C. in an argon atmosphere to form a graphite-TiB 2 composite cathodic element.

Claim 21

A process of manufacturing a cathodic TiB 2 -graphite element for a Hall aluminum cell comprising dispersing TiO 2 and coke particles in molten coal tar pitch to form a plastic mass, forming said element by molding or extrusion, baking said element on a rising temperature cycle over a period of 1 to 10 days, the temperature reaching from 700° to 1100° C., cooling said element, impregnating said element under alternate cycles of vacuum and a pressure of from 1.7 to 6.9×10 5 Pa with a boron compound selected from the group consisting of molten B 2 O 3 , at approximately 500° C., molten H 3 BO 3 at approximately 500° C., B 2 O 3 in water solution, H 3 BO 3 in water solution, and B 4 C dispersed in molten petroleum pitch, drying said element at a temperature of approximately 100° C. if a water solution was used when impregnating said element, re-baking said element on a 1 to 10 day cycle, rising to 700° to 1100° C., heating said element to approximately 1750° C., cooling, and re-impregnating said element with said molten petroleum pitch, baking said element over a 1 to 10 day cycle, rising to 700° to 1100° C., and heating to approximately 2250° C. to form said TiB 2 -graphite element.

Claim 22

A process of manufacturing a cathodic TiB 2 -graphite element for a Hall aluminum cell comprising dispersing TiO 2 and coke particles in molten coal tar pitch to form a plastic mass, forming said element by molding or extrusion, baking said element on a rising temperature cycle over a period of 1 to 10 days, the temperature reaching from 700° to 1100° C., cooling said element, impregnating said element under alternate cycles of vacuum and a pressure of from 1.7 to 6.9×10 5 Pa with a boron compound selected from the group consisting of molten B 2 O 3 , at approximately 500° C., molten H 3 BO 3 at approximately 500° C., B 2 O 3 in water solution, H 3 BO 3 in water solution, and B 4 C dispersed in molten petroleum pitch, drying said element at a temperature of approximately 100° C. if a water solution was used when impregnating said element, re-baking said element on a 1 to 10 day cycle, rising to 700° to 1100° C., heating said element to approximately 1750° C., cooling, and re-impregnating said element with said molten petroleum pitch, baking said element over a 1 to 10 day cycle, rising to 700° to 1100° C., and heating to approximately 2250° C. to form said TiB 2 -graphite element.