Ti (C,N)-based Cermets Composite Powder Prepared By Sol-gel Method

In this paper, Ti （C,N）-base of cermets composite powders havebeen prepared by sol-gel method,carbon thermal and sintering, useingthe raw materials of titanium tetrabutoxide,sugar, ammoniummolybdate,and nickel nitrate.Studied the evolution process of TiO₂â†'TiCâ†'Ti （C,N）-base of ceramic composite powder,analyzed its initialreaction mechanism. The Ti （C,N）-base of ceramic composite powderinfluence factors have been determine by adopt orthogonal experiment.During the process of microwave sintering in sol precursor, the phase ofcomposite powers caused by added different dissolved salt. Thepreliminary formation mechanism, the thermodynamic and the heatpreservation process are discussed in this paper. The results as showing:（1） During the pioneer of nanometer TiO₂powder preparationprocess, acetic acid as a stabilizer of the hydrolysis of tetrabutyl titanatesolution involved in inhibition of hydrolysis, at pH=3,sol–OR titaniumbase by the aggregation of partly replacing acetate acetic acid. Preceramicpolymer powder happened at about275℃, alcohol condensation waterloss and condensation, the weightlessness rate was30%; At450℃in theanatase from ruby to crystal shape. At900℃of the rutile content is about90%, the content of anatase is about10%;400℃when the grain size of18nm, at900℃for21nm, grain size, as the temperature rises.（2） During the TiC powder preparation process with the increase oftemperature of the phase evolution order of samples is: TiO₂Anataseâ†'TiO₂Rutileâ†'Ti_xO_y（x=2and4; y=3,5,7）; From the point of theselection of carbon sources, sucrose under low temperature （1400℃） cangenerate Ti（C0.7,N0.3） and carbon black can’t generate; Throughthermodynamics theory calculation and analysis combined with XRD results, preparation of carbon in the TiC in dicating the main chemicalreaction as TiO₂（s）+3C（s）â†'TiC （s）+2CO （g）.（3） During the Ti （C,N）-base ceramic powder preparation process inconventional heating, the process parameters optimization have beendetermine by orthogonal experiment: when the pH=4; m （H2O/Ti （theOBu）4）=6; the gel time was short and particles were best. With sol-gelmethod combined with the carbon thermal reduction process under1400℃, the preparation of Ti （C,N）-Mo2C-Ni metal ceramic powder werehigh purity and from molecular or atomic level mixing metal bonds.（4） in the microwave sintering preparation of Ti （C,N） cermetpowder when KCl molten salt to join, at1250℃, the heat preservationfor30minutes every new phase in the TiN, produce the chemical reaction,showed that the oxygen Ti_xO_yreplaced by nitrogen atoms. When haveNaCl to join, at1250℃, the heat preservation was30minutes Ti （C,N）phase, under low temperature （1250℃） chemical reaction happens, thatNaCl molten salt with microwave sintering can reduce formation of Ti（C,N） phase reaction temperature. Also found in the microwave sinteringpreparation of Ti （C,N） fund of ceramic composite powders, with NaCl asthe molten salt can join at1250℃. When have NaCl to join, at1250℃,under different heat preservation time, the results show that as thelengthen of time of heat preservation, Ti_xO_yphase gradually replaced bythe Ti （C,N） phase. When the holding time at2hours, mainly for the Ti（C,N） powder-Mo-Ni metal composite ceramic composite powder. Byno ball mill in the powder morphology found some powder into squares,have reunion phenomenon, part of the particles is small, under0.02μ size.