爆炸喷涂Al-Cu-Cr准晶涂层的组织及硬度研究

Microstructure and hardness properties of detonation spraying AI-Cu-Cr quasicrystalline coatings

为了研究热喷涂工艺对爆炸喷涂Al-Cu-Cr准晶涂层组织和硬度的影响规律,采用三种爆炸喷涂工艺参数在Q235A低碳钢基体上制备涂层,借助XRD、SEM和OM等技术手段对粉末和涂层的组织结构进行分析,并检测涂层横截面的孔隙率和显微硬度。结果表明,用于喷涂的Al_(65)Cu_(20)Cr_(15)准晶粉末中含有二十面体准晶相i-Al_(65)Cu_(24)Cr_(11)和极少量具有单斜结构的晶体相θ-Al_(13)Cr_2(即Al_(83)Cu_4Cr_(13));而爆炸喷涂涂层中除i和θ两相外,生成了新相——体心立方结构的α-Al_(69)Cu_(18)Cr_(13)(准晶i的晶体类似相)和Al_2O_3相。涂层呈典型层状结构,其它条件不变的情况下,涂层中各晶体相与准晶相i最强峰衍射强度的比值α/i、θ/i和Al_2O_3/i随爆炸喷涂工作气体流速的成比例提高而增加,同时涂层截面的孔隙率下降而显微硬度HV_(0.1)升高。

In order to investigate the influence of detonation spraying parameters on the microstructure and hardness properties of the coatings, different process parameters were respectively used to deposit Al-Cu-Cr quasicrystalline coatings on the .Q235A low carbon steel. The microstructure of the coatings and feedstock powders were characterized by means ofXRD, SEM and OM. The cross section porosity levels and microhardness HVo.1 of the coatings were measured. The results show that, the starting powders consist of a dominant icosahedral quasicrystalline phase i-A165Cu24Cr11and a minor monoclinic crystalline phase θ-Al13Cr2 （i.e. AIs3Cu4Cr13）. However, besides these two phases, an approximant to i-Al65Cu24Cr11, α-Al69Cu18Cr13 （body-centered cubic） and Al2O3 have been detected in all coatings. On the other hand, all the coatings take lamellar structures as characteristics, and for identical spraying conditions, as the working gases （i.e. C2H2, O2, N2 and air） flow rates were proportionally increased, the peak intensity ratio of the strongest peak of each crystalline phase to the i-phase, such as α/i, θ/i and Al2O3/i rose, and the coatings cross section microhardness HVo.1 increased but the porosity decreased.