Ta涂层对CVD单晶金刚石焊接强度的影响  

Effect of Ta Coating on Welding Strength of CVD Single-crystal Diamond

作　　者：毛雅梅 黑鸿君[1] 高洁[1,2] 张孟 王垚 郑可 于盛旺[1] MAO Ya-mei;HEI Hong-jun;GAO Jie;ZHANG Meng;WANG Yao;ZHENG Ke;YU Sheng-wang(College of Materials Science and Engineering,Taiyuan University of Technology,Taiyuan 030024,China;National Key Laboratory of Science and Technology on Vacuum Electronics,University of Electronic Science and Technology,Chengdu 610054,China)

机构地区：[1]太原理工大学材料科学与工程学院,太原030024 [2]电子科学技术大学真空电子科学技术国家重点实验室,成都610054

出　　处：《表面技术》2022年第11期445-451,共7页Surface Technology

基　　金：国家自然科学基金(51901154);山西省自然科学基金(201901D211092);山西省科技重大专项(20181102013);“1331项目”山西省工程研究中心资助项目(PT201801)。

摘　　要：目的提高金刚石的可焊性,促进金刚石与异质合金的连接。方法采用双辉等离子体表面合金化(DGPSA)技术在CVD单晶金刚石表面沉积Ta_(2)涂层,然后利用Ag–Cu–Ti(Ti的质量分数为2%)钎料合金将Ta_(2)涂层单晶金刚石与硬质合金(WC–Co)在真空钎焊炉中进行焊接。采用X射线衍射仪、扫描电子显微镜和能谱仪分析Ta_(2)涂层及焊后截面的物相组成、表面微观形貌、截面微观形貌、元素分布。使用万能试验机对有Ta_(2)涂层和无Ta_(2)涂层的焊后样品进行剪切断裂试验,对焊接后样品的界面结合强度进行探究。结果在合金化温度为850℃下,随着沉积时间(5、15、30、60 min)的延长,Ta_(2)涂层的厚度从0.35μm增至7.96μm,晶粒由纳米晶转变为柱状晶,整个涂层由沉积层Ⅰ和扩散层Ⅱ组成,且在金刚石/Ta_(2)涂层界面处生成了2种力学性能良好的金属型碳化物,即Ta_(2)C和Ta_(2)C。焊接接头的剪切强度随着Ta_(2)涂层沉积时间的延长,呈先增大后减小的趋势。结论当沉积时间为30 min时,Ta_(2)涂层的厚度为3.47μm,与WC–Co焊接后其剪切强度达到最大值(115.6 MPa),且大于无Ta_(2)涂层焊接样品的剪切强度(75.6 MPa),证明Ta_(2)涂层对单晶金刚石的可焊性有明显的促进作用。The work aims to improve the weldability of diamond and facilitate the bonding between the diamond and heterogeneous alloy.Ta_(2) coating was deposited on chemical vapor deposition(CVD)single-crystal diamond(not powder or particle)surface with large-size via double glow plasma surface alloying(DGPSA)technique.Then,the Ta_(2)-coated single-crystal diamond and cemented carbide(WC-Co)were brazed with Ag-Cu-2wt.%Ti brazing alloy at 810 ℃ for 10 min in vacuum furnace.The phase composition,surface micro morphology and element distribution of Ta_(2) coating and the cross-sectional morphology after brazing were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and energy dispersive X-ray spectrum(EDS).Furthermore,to verify the effectively weldability of Ta_(2) coating for single-crystal diamond,a universal testing machine was used to conduct a shear fracture test on the brazing samples of single-crystal diamond with Ta_(2) coating and without Ta_(2) coating(control group)to explore the interfacial bonding strength after brazing.After alloying at 850℃,the thickness of Ta_(2) coating increased gradually from 0.35μm to 7.96μm for deposition of 5,15,30 and 60 min,the grain grew from the nano-crystal to columnar crystal,and the average grain size increased from~84.24 nm to~136.11 nm according to the XRD pattern and Scherrer's equation with the deposition time at the same temperature of alloying(850℃).The surface of Ta_(2) coating sags and crests increased with the increase of deposition time and this surface unevenly improved the flow of brazing alloy and enhanced the adhesion between Ta_(2)-coated single-crystal diamond and WC-Co during brazing.Besides,combined with the SEM of cross-sectional morphology and EDS,the Ta_(2) coating was composed of deposited layer Ⅰ and diffused layer Ⅱ.This diffused layer was mainly composed of Ta_(2)C and Ta_(2)C.These two metal carbides with good mechanical properties were generated at the single-crystal diamond/Ta_(2) coating interface.The Ta_(2)C had mech

关 键 词：CVD单晶金刚石 双辉等离子体表面合金化 Ta涂层 Ag–Cu–Ti钎料合金 真空钎焊 结合强度 

分 类 号：TG113.263[金属学及工艺—物理冶金]