Polycrystalline Sic Electrical Devices and Methods for Fabricating the Same

Abstract

The present invention relates to a to novel electrical devices fabricated from polycrystalline silicon carbide (SiC) and methods for forming the same. The present invention provides a method for fabricating polycrystalline silicon carbide (SiC) products infiltrated with SiC-containing preceramic precursor resins to substantially mask the deleterious effects of trace contaminants, typically nitrogen and aluminum, while reducing operative porosity and enhancing manufacturing ease.

1 . A process for manufacturing a ceramic body, comprising the steps of:
 forming a porous ceramic body comprising SiC particles having an open porosity;   infiltrating said ceramic body with an SiC-precursor resin;   curing said infiltrated ceramic body at a peak temperature between approximately 200° C. to 400° C.; and   pyrolyzing said cured and infiltrated ceramic body at a temperature as low as 650° C. in an inert atmosphere to form a ceramic-bonded particulate ceramic composite body, whereby said step of pyrolyzing forms a permanent amorphous SiC bonding phase at temperatures as low as 650° C. enabling an improved operational strength within a pre-recrystallization temperature range of between 650° C. and 2000° C.   
   
   
       2 . A process for manufacturing a ceramic body, according to  claim 1 , further comprising the step of:
 conducting at least one repetition of said steps of infiltrating, curing, and pyrolyzing whereby said ceramic body increases in density.   
   
   
       3 . A process for manufacturing a ceramic body, according to  claim 1 , wherein:
 said SiC-precursor resin is at least one of a group comprising:
 a allylhydrido-polycarbosilane (AHPCS) resin, a allylhydrido-polycarbosilane (AHPCS) resin type SMP-10 supplied by Starfire Systems; a variant suspension formed by adding at least one of very fine alumina or aluminum particles in an AHPCS resin prior to said step of infiltrating; an admixture suspension of a compatible organo-aluminum compound with an AHPCS resin; and an improved resin formed by incorporating aluminum compounds onto a backbone of an AHPCS resin polymer itself. 
   
   
   
       4 . A process for manufacturing a ceramic body, according to  claim 3 , further comprising the steps of:
 recrystallizing said ceramic body at a minimum temperature of 1800° C. in an inert gas atmosphere.   
   
   
       5 . A process for manufacturing a ceramic body, according to  claim 4 , further comprising the step of:
 conducting at least one repetition of said steps of infiltrating, curing, and pyrolyzing at a first time period, whereby said ceramic body increases in density.   
   
   
       6 . A process for manufacturing a ceramic body, according to  claim 4 , further comprising the step of:
 conducting at least one repetition of said steps of infiltrating, curing, and pyrolyzing at a first time period, whereby said ceramic body increases in density; and   said first time period is at least one of a time period before a first recrystallization step and a time period after said first recrystallization step.   
   
   
       7 . A ceramic body, comprising:
 a porous polycrystalline SiC-ceramic body having open porosity and containing at least one of an alpha phase SiC and a Beta phase SiC material;   a bonding phase impregnated in said SiC-ceramic body containing an amorphous SiC matrix material at 650° C. forming a ceramic-bonded particulate ceramic composite.   
   
   
       8 . A method for manufacturing an impregnated body, comprising the steps of:
 providing a porous ceramic body having open porosity;   impregnating said ceramic body with an organo-metallic resin;   curing said impregnated ceramic body at a peak temperature between approximately 200° C. to 450° C.; and   pyrolyzing said ceramic body at a temperature as low as 650° C. to form a ceramic-bonded particulate ceramic composite bisque product, whereby said step of pyrolyzing forms a permanent bonding phase at temperatures as low as 650° C. enabling an improved process strength.   
   
   
       9 . A method for manufacturing an impregnated body, according to  claim 8 , wherein:
 said ceramic body is a SiC-body and said organo-metallic resin is a SiC-precursor resin.   
   
   
       10 . A method for manufacturing an impregnated body, according to  claim 9 , wherein:
 said SiC-precursor resin is allylhydrido-polycarbosilane (AHPCS) polymer resin.   
   
   
       11 . A method for manufacturing an impregnated body, according to  claim 9 , wherein said method further comprises the step of:
 recrystallizing said ceramic body at a minimum temperature of 1800° C. in an inert gas atmosphere.   
   
   
       12 . A method for manufacturing an impregnated body, according to  claim 8 , further comprising the step of:
 conducing at least one repetition of said steps of impregnating and curing, whereby said step of conducing results in an increased density of said impregnated body relative to a pre-conducting-step density.   
   
   
       13 . A method for manufacturing an impregnated body, according to  claim 12 , further comprising the step of:
 recrystallizing said ceramic body at a minimum temperature of 1800° C. in an inert gas atmosphere.   
   
   
       14 . A method for manufacturing an impregnated body, according to  claim 13 , further comprising the step of:
 conducing at least one repetition of said steps of impregnating and curing prior to said step of recrystallizing, whereby said step of conducing results in an increased density of said impregnated body following said subsequent recrystallization step relative to a pre-conducting-step density.   
   
   
       15 . A method for manufacturing an impregnated body, according to  claim 8 , wherein said step of pyrolyzing said ceramic body is conducted in a non-oxidizing atmosphere. 
   
   
       16 . A method for manufacturing an impregnated body, according to  claim 13 , wherein said step of recrystallizing said ceramic body is conducted in a non-oxidizing atmosphere. 
   
   
       17 . A method for manufacturing an impregnated body, comprising the steps of:
 providing a porous ceramic body having open porosity;   impregnating said ceramic body with an organo-metallic resin;   curing said impregnated ceramic body at a peak temperature between approximately 200° C. to 450° C. in an inert atmosphere;   pyrolyzing said ceramic body at a temperature as low as 650° C. in an inert atmosphere to form a ceramic-bonded particulate ceramic composite bisque product, thereby forming a permanent bonding amorphous phase at temperatures as low as 650° C. enabling an improved process strength;
 said pyrolized ceramic body having a first wide cross-section portion and a second narrow cross-section portion perpendicular to the first cross-section; 
   orienting said pyrolized ceramic body in a recrystallization furnace in a first orientation with said first wide cross-section portion parallel to the field of gravity; and   recrystallizing said ceramic body at a minimum temperature of 1800° C. in an inert gas atmosphere, whereby said amorphous phase enables said recrystallization step without orienting said first wide cross-section portion perpendicular to said field of gravity.   
   
   
       18 . A method for manufacturing an impregnated body, according to  claim 18 , wherein said step of orienting further comprises the steps of:
 positioning a plurality of said pyrolized ceramic bodies in said first orientation whereby respective said first wide cross-section portions contact respective first wide cross-section portions of adjacent pyrolized ceramic bodies prior to said step of recrystallizing.