Study On Wrapper And Method Of Adding Ti, V At Lower Temperature In Preparation Process Of In Situ TiCp/Fe,VCp/Fe Composites

Because of the easy technique, lower price, and better properties, using in-situ action foundry to produce ferrous matrix composites is one of the interesting topics. Having the high hardness, high module, high melting temperature, high anti-bending intensity, and better wear resistance properties, TiC, VC particles are used as the reinforced phase of the ferrous matrix composites. But Ti, V are active and easily oxygenated, so Ti, V are burned seriously in foundry process, the chemical quantities of Ti, V that the author designed can not be attained, and the production cost is enhanced. At the same time, Ti, V are burned seriously, so C is excessive which result in the harmful phase (graphite) exists in the matrix.The article aims at decreasing the burning loss ratio in in-situ foundry process, kinds of different wrappers are designed, their anti-oxygenate and anti-burning properties are compared, at the same time preparation process of adding Ti, V into the composites at lower temperature are studied. The results are as following:1.Ash + charcoal is choose as the optimal wrapper of anti-oxygenation and anti-burning properties, this operation is easier and burning loss ratio of Ti is only 17.1% by using this wrapper. This technics achieves domestic high level.2.Action mechanisms of wrappers in anti- oxygenation and anti-burning are discussed. The effect of the wrappers should have reduction, besides isolating O₂ come into the alloy melting liquid. Wrappers containing C or graphite this kind of reducing agent can reduce Ti_xO_y which produced in the alloy melting liquid and float to the fluid surface, besides isolating O₂ in the air to come into the alloy melting liquid, so the effects of this wrapper in preventing Ti oxygenating and burning are much better.3.The process of adding Ti at lower temperature is discussed. The result indicates that the effects of adding Ti into the composites to prevent oxygenation and burning at lower temperature (this technique has applied for patent) achieved the highest level domestic now, the burning loss ratio of Ti is only 12.3%.4.The reaction mechanisms of adding Ti at lower temperature are discussed from three aspects such as reaction thermodynamics, dynamics and diffusion mechanism. At lower temperature the produce of TiC particles mainly depends on diffusion reaction. Because the radius of C atom is relatively small, C atoms mainly diffuse by gap and vacancy mechanisms, while Ti atoms mainly diffuse by vacancy mechanisms because of the relatively bigger radius.5.The process of adding V at lower temperature is discussed. The result indicates that the burning loss ratio of V is only 9.1%.