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PRODUCTION OF ULTRA-FINEα-AL2O3 PO WDERSFROM AMMONIUM A LUMINUM CARBONATE HY DROXIDE

F. Zhang1) , X. D. Sun1) , J. You2) , Z. Zhang2) , L. X. Ding3)and Y. M. Wang3)1) School of Materials and Metallurgy , Northeastern University , Shenyang 110006 , China2) Liaoning Analyzing and Testing Research Center , Shenyang 110015 , China3) Department of Materials , School of Mechanical Engineering , Shenyang University , Shenyang 110044 , China

金属学报(英文版)

Synthesis of a m m oniu m alu min u m carbonate hydroxide ( A A C H) w as investigated usinga m m oniu m alu min u m sulfate and a m moniu m hydro carbonate as the starting m aterials . Itw as found that A A C Hcan be synthesized by adding a m m oniu m alu m inu m sulfate solution torapidly stirred a m moniu m hydro - carbonate solution at a tem perature of 30 ℃. A A C Hcantransfor m to α Al2 O3 co m pletely by calcining at 1100 ℃ for 1 hour , and the obtained po w ders , with a particle size of 100 n m , can be sintered to 98 99 % relative density at 1500 ℃for 2 hours .

关键词: a m moniu m alu m inu m carbonate hydroxide , null , null , null

EFFECT OF PRECIPITANT ON THE PROPERTIES OF ULTRAFINE YTTRIA POW DER PRODUCED BY PRE CIPITATION METHOD

Y. Q. Jia1) , J. G. Li1) , Y. M. Wang2) , L. X. Ding2) , X. M . Qin1) and X. D. Sun1)1) School of Materials and Metallurgy , Northeastern University , Shenyang 110006 , China2) Department of Materials , School of Mechanical Engineering , Shenyang University , Shenyang 110044 , China

金属学报(英文版)

Using yttriu m nitrate as the m other salt , synthesis of ultrafine yttria po w der through w et che mical route w as investigated . Choice of precipitant has dra m atic effects on co m position ,particle size distribution and particle m orphology of the precipitates . When a m m onia solutionw as used as the precipitant , the precursor precipitate w as m ainly Y2( O H) 5 14( N O3) 0 86· H2 O with co m paratively large particle size , broad size distribution and co m plex particleshapes . When sodiu m hydroxide solution w as used , roughly spherical α Y( O H)3·3 H2 Opre cipitate w ith sm all particle size and narro w size distribution w as obtained . The transfor m a tion sequence of dry α Y( O H)3 ·3 H2 O gel during calcination w as determ ined to be α Y( O H) 3·3 H2 O→ Y O O H→ Y2 O3 . After calcining at 600 ℃ for 1 hour , both Y2( O H) 5 14( N O3) 0 86· H2 O and α Y( O H) 3·3 H2 O transfor m to well crystallized Y2 O3 pow ders ,w ith particle sizes of 50 ～3000 n m and 20 n m , respectively .

关键词: KEYW ORDS yttria , null , null , null

DIRECT SYNTHESIS OF SIA LON/ SiC MULTIPHASE REF RACTORY USING CLAY

H. Q. Ru1) , N. Zhang2) , P. Z. Yu1) and X. D. Sun1)1) Northeastern University , Shenyang 110006 , China2) Shenyang University , Shenyang 110044 , China

金属学报(英文版)

Sialon/ Si C m ultiphase refractory w as directly synthesized using cheap clay , Si C particlesand proper ad ditives . The new synthesizing process is si m ple an d of low cost . The synthesizedm aterial has good roo m tem perature m echanical properties and ther m al shock resistance . Thisw ork has provided the experi mental basis for the ap plication of high property an d cheap Sialon/ Si C m ultiphase refractories .

关键词: clay , null , null

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