TiB2粉末化学镀银工艺研究

采用化学镀银法制备Ag/TiB2复合粉末,系统研究NaOH,HCHO,NH.3H2O的加入量及反应时间等参数对包覆粉末质量的影响及TiB2表面改性对AgTiB2材料性能的影响。结果表明:NaOH和HCHO含量的增加可促进Ag的还原反应;pH值的大小对Ag的还原有显著的影响,pH值大可加快反应过程,使Ag的还原更加彻底;NH3.H2O在化学镀银过程中起稳定作用,随着NH3.H2O的增加,使反应液更为稳定,Ag不易发生自分解,但也导致镀银溶液中主盐的Ag不容易被还原,不能获得Ag均匀包覆的TiB2复合粉末;反应时间的延长对于反应后粉末中Ag含量的增加影响并不十分明显。采用化学镀的粉末所制备的Ag/TiB2复合材料的致密度、硬度和电导率分别提高了4.59%,12.20%和7.91%。

Electroless silver plating of TiB2 powders

Ag/TiB2 compound powders were prepared by electroless silver plating on TiB2 powders.The effect of adding NaOH,HCHO,NH3·H2O and reaction time on the quality of powder coating was studied,and the effect of the modified TiB2 powders on the properties of AgTiB2 composite was investigated as well.The morphology of Ag/TiB2 powders and microstructure of Ag/TiB2 composite were characterized by means of scanning electronic microscopy(SEM).The results show that higher NaOH and HCHO content can promote the reduction reaction of Ag.However,pH value also has obvious affect on the reduction reaction of Ag.Larger pH value can accelerate the reaction process and cause more complete Ag reduction.NH3·H2O can play a role in stability during the silver plating process.With the increase of NH3·H2O,the reaction solution becomes more stable,and less Ag is prone to self-decomposition.Nevertheless,more NH3·H2O content causes the difficulty of silver salt solution Ag to be reduced,and non-uniform Ag-coated TiB2 composite powders are formed.Reaction time has no obvious effect on the Ag increment.The optimal process were given parameters.Compared to the AgTiB2 composite prepared by no Ag-coated TiB2 powders,the Ag/TiB2 composite prepared by electroless Ag plating has better properties,and density,hardness,and electrical conductivity are increased by 4.59%,12.20% and 7.91%,respectively.