KOH／K2ZrF6对TC4钛合金微弧氧化膜层形貌和结合强度的影响

研究电解液中添加KOH及K₂ZrF₆对TC4钛合金微弧氧化膜层形貌及结合强度的影响。选用硅酸盐-磷酸盐复合盐为主盐,添加甘油作为辅助试剂,分别配制两种均不添加、只添加KOH、只添加K₂ZrF₆和两种物质均添加的4种电解液对TC4钛合金进行微弧氧化处理。通过膜层厚度、膜层表面粗糙度、膜层硬度、膜层与基体的结合强度等检测,对比分析不同膜层的综合性能,并通过扫描电子显微镜、能谱仪及X射线衍射仪等对膜层物相进行对比分析。结果表明:在硅酸盐-磷酸盐复合盐为主盐的电解液中,氧化30 min后,添加KOH试剂使微弧氧化反应起弧电压从350 V降低至300 V,膜层表面粗糙度Ra为1.66μm,结合强度为29 MPa,膜层硬度866HV,厚度19μm。添加K₂ZrF₆试剂使微弧氧化的起弧电压提高至380 V,膜层表面粗糙度Ra为2.47μm,结合强度为18 MPa,膜层硬度992HV,厚度为26μm,同时,氧化反应生成ZrO₂,可大幅提高膜层硬度。添加KOH和K₂ZrF₆试剂可以影响微弧氧化反应起弧电压及工作电压,进而影响膜层的组织形貌,从而改善膜层的表面粗糙度和厚度以及结合强度,硬度等性能。

Effect of KOH / K2ZrF6 on the structure and bonding strength of micro-arc oxide film of TC4 titanium alloy

The effect of the addition of KOH and K₂ZrF₆ in the electrolyte on the structure and bonding strength of TC4 micro-arc oxide film of titanium alloy.The silicate-phosphate complex salt was chosen as the main salt and glycerol was added as the auxiliary reagent.Four kinds of electrolytes without KOH and K₂ZrF₆,with KOH,with K₂ZrF₆,and with both additions were prepared to perform micro-arc oxidation on TC4 alloy.The comprehensive properties of different coatings were compared and analyzed by testing the thickness,surface roughness,hardness and bonding strength between the coatings and the substrate.The structure of the coatings was compared and analyzed by scanning electron microscopy,energy dispersive spectrometer and X-ray diffraction.The results showed that with the addition of KOH reagent,the arc starting voltage of the micro-arc oxidation reaction was reduced from 350 V to 300 V,the surface roughness Ra,the binding strength,the surface hardness,and the thickness was 1.66μm,29 MPa,866 HV,and 19μm,respectively.With the addition of K2ZrF6 reagent,the arc starting voltage of micro-arc oxidation was increased to 380 V,the surface roughness Ra,the binding strength,the hardness,and the thickness of the film was 2.47μm,18 MPa,992 HV,and 26μm,respectively.At the same time,the oxidation reaction generated ZrO₂,which could greatly improve the hardness of the film.The addition of KOH and K₂ZrF₆ reagents can affect the arc starting voltage and working voltage of the micro-arc oxidation reaction,and further affect the microstructure of the film,causing the improvement in the surface roughness,thickness,binding strength,hardness and other properties of the film.