添加相对自蔓延成型铝合金筒内壁涂层温度的影响

Temperature effect analysis of additives in self-propagating forming aluminum alloy cylinder inner wall coating

自蔓延高温通常约为1000℃,超过铝合金筒的可承受温度502~638℃,对铝合金基体造成热损伤,而Si、Ti与Mo作为添加相,可通过活化晶格和润湿界面来降低自蔓延铝热反应温度。采用低温自蔓延技术制备小内径的铝合金管内壁耐磨涂层,探讨了添加相(Si、Ti与Mo)对降低自蔓延铝热反应体系温度的影响。利用正交试验确定了铝热剂、添加相最佳配比与冷却压力等工艺参数,研究了添加相的降温机理。结果表明:传统铝热反应过程释放热量较大,加入Si、Ti添加相可以降低反应温度,会减缓反应剧烈程度,甚至抑制反应的进行,加入适量Mo时会使铝热反应重新发生。加入全部添加相的自蔓延反应体系的放热反应温度较铝热反应温度降低了100℃左右且高温失重最少,为1.33%。最优配比为:冷却气体压力为0.2 MPa,添加相质量分数为6%,铝热剂质量分数为94%。

The high temperature of self-propagation is about 1000℃,which exceeds the tolerable temperature of 502-638℃of the bearing temperature of aluminum alloy tube and causes thermal damage to the aluminum alloy substrate,while Si,Ti and Mo,as the additive phases,can reduce the temperature of self-propagation aluminum thermal reaction by activating the crystal lattice and wetting the interface.In this paper,low-temperature self-propagation technology is used to prepare wear-resistant coatings on the inner wall of aluminum alloy tubes with small inner diameters,and investigated the effect of added phases(Si,Ti,and Mo)on reducing the temperature of the self-propagating aluminothermal reaction system.Orthogonal experiments were used to determine process parameters such as the optimal ratio of aluminothermic agents,additive phases,and cooling pressure,and the cooling mechanism of additive phases was studied.The results show that the traditional aluminothermic reaction process releases a large amount of heat.Adding Si and Ti phases can lower the reaction temperature,slow down the severity of the reaction,and even inhibit the progress of the reaction.Adding an appropriate amount of Mo will cause the aluminothermic reaction to occur again.The Exothermic reaction temperature of the self-propagating reaction system with all added phases is about 100℃lower than that of the aluminothermic reaction,and the weight loss at high temperature is at least 1.33%.The optimal ratio is:the cooling gas pressure is 0.2 MPa,the mass fraction of the added phase is 6%,and the mass fraction of thermite is 94%.