A PROCESS FOR MAKING SINTERED SILICON CARBIDE-PRASEODYMIUM OXIDE-ALUMINUM OXIDE COMPOSITES USEFUL AS ENGINEERING CERAMICS

摘要

The present invention relates to a process for making sintered silicon carbide-praseodymium oxide-a aluminum oxide composites. The process steps are: preparing a suspension of a mixture of SiC & A12O3 in praseodymium nitrate solution wherein praseodymium oxide equivalent to praseodymium nitrate solution and alumina used are 5 to 25 percent by wt. of SiC, maintaining a pH in the range of 7.35 to 8.00, pouring this suspension in ammonium hydroxide solution to obtain a gel-like mass, ageing the gel-like mass for a period in the range of 8-24 hours, filtering and washing the aged gel-like mass, drying the material at a temperature in the range of 100± 5°C for 8-12 hours, grinding the dried mass to pass through 100 mesh B.S., pelletizing by known methods the ground mass isostatically under 180-250 MPa, sintering the pressed pellets so obtained at a temperature in the range of 1750-1950°C for a period in the range of 0.25 hour to 1 hour in an inert atmosphere, the said process characterized in that in using praseodymium oxide and sintering at a temperature range of 1750-1950°C.