金刚石对Ni-Al自蔓延反应过程的影响

Effect of adding diamond grits on Ni-Al powders using SHS technique

本研究主要针对Ni-Al自蔓延反应燃烧过程和加入金刚石磨料后的变化,其反应产物的微观形貌,以及SHS反应后金刚石的表面特征及强度的变化进行的探讨。结果表明:添加含量大于15%的金刚石时,Ni-Al体系的燃烧波速度和燃烧温度均随金刚石含量的增大而降低,呈现出振荡燃烧模式。添加含量小于15%的金刚石时,Ni-Al体系燃烧波速度和燃烧温度影响不大,呈现出稳态燃烧模式。添加20%金刚石Ni-Al体系的SHS反应产物主要有NiAl、Ni2Al3、Ni3Al和NiAl3。SHS反应的瞬时高温使一部分金刚石表面由黄色变成了褐色或黑色,且在金刚石表面产生了较多蚀坑,而蚀坑表面由很多球状颗粒。金刚石的平均抗压强度比SHS反应前降低了23%。

Effect of diamond grits as an additive on Ni-Al SHS reaction process was studied.The morphology of reaction products as well as the surface morphologies and the compressive strength of diamond after reaction were investigated.The results show that the flame-front propagation velocity and the combustion temperature of Ni-Al decreases with the increase of content of the diamond grits,when their content is more than 15%（mass fraction）,and the propagation is in an oscillating mode.However,the diamond content less than 15% has little effect on the flame-front propagation velocity and the combustion temperature of Ni-Al,and the propagation is in a steady mode.Intermetallics such as NiAl,Ni2Al3,Ni3Al and NiAl3 are identified in the reacted Ni-Al/diamond composite.The surface colour of some diamond grits is changed from brown to black,because of the instantaneous high temperature of SHS.There are a large number of craters on diamond grits＇ surface,in which spherical particles are found.After the reaction of SHS,the mean compressive strength of diamond grits is found decreased by 23% compared with the initial diamond grits.