超硬磨具激光增材制造过程中,金刚石极易受到激光直接辐照和高温熔池的影响,出现石墨化等热损伤现象.选取典型的金刚石磨具用金属结合剂CuSn10粉末,采用粉末床熔融(Powder Bed Fusion-laser Beam,PBF-LB)技术制备CuSn10-金刚石复合材料...超硬磨具激光增材制造过程中,金刚石极易受到激光直接辐照和高温熔池的影响,出现石墨化等热损伤现象.选取典型的金刚石磨具用金属结合剂CuSn10粉末,采用粉末床熔融(Powder Bed Fusion-laser Beam,PBF-LB)技术制备CuSn10-金刚石复合材料;围绕高能激光束和高温熔池两个影响增材制造过程中金刚石颗粒性能的关键因素,以单颗金刚石颗粒为研究对象,通过有限元模拟分析构建金刚石颗粒的温度场模型,反映了金刚石颗粒在PBF-LB中的热演化过程;阐明了PBF-LB过程金刚石的热损伤机制,发现金刚石发生石墨化转变并不是由激光的直接辐照造成的,而是由高温熔池的热影响导致,CuSn10-金刚石复合材料在PBF-LB过程中石墨化的临界温度为1491.6℃.建立了PBF-LB工艺-金刚石颗粒温度-石墨化程度-摩擦磨损性能的定量关系,发现随着金刚石颗粒温度的增加,其石墨化程度增加,严重损害了复合材料的摩擦磨损性能.展开更多
The ohmic contact interface between diamond and metal is essential for the application of diamond detectors.Surface modification can significantly affect the contact performance and eliminate the interface polarizatio...The ohmic contact interface between diamond and metal is essential for the application of diamond detectors.Surface modification can significantly affect the contact performance and eliminate the interface polarization effect.However,the radiation stability of a diamond detector is also sensitive to surface modification.In this work,the influence of surface modification technology on a diamond ohmic contact under high-energy radiation was investigated.Before radiation,the specific contact resistivities(ρc)between Ti/Pt/Au-hydrogen-terminated diamond(H-diamond)and Ti/Pt/Au-oxygenterminated diamond(O-diamond)were 2.0×10^(-4)W·cm^(2) and 4.3×10^(-3)Wcm^(2),respectively.After 10 MeV electron radiation,the ρc of Ti/Pt/Au H-diamond and Ti/Pt/Au O-diamond were 5.3×10^(-3)W·cm^(2)and 9.1×10^(-3)W·cm^(2),respectively.The rates of change of ρc of H-diamond and O-diamond after radiation were 2550%and 112%,respectively.The electron radiation promotes bond reconstruction of the diamond surface,resulting in an increase in ρc.展开更多
采用热丝化学气相沉积法制备了含有钽原子的石墨烯竖立片层,并将其置于含氧环境中进行退火处理,在常压环境中发生相变得到纳米金刚石,并研究退火环境中氧含量变化对纳米金刚石形成的影响.结果表明,当退火环境气压为10 Pa和50 Pa (对应...采用热丝化学气相沉积法制备了含有钽原子的石墨烯竖立片层,并将其置于含氧环境中进行退火处理,在常压环境中发生相变得到纳米金刚石,并研究退火环境中氧含量变化对纳米金刚石形成的影响.结果表明,当退火环境气压为10 Pa和50 Pa (对应氧原子百分比为1.96%和2.04%)时,退火后样品形貌与结构和未处理的石墨烯片层无异;样品100 Pa和500 Pa气压下退火后(对应氧原子百分比为2.77%和3.11%),在其中观察到了尺寸为2—4 nm的纳米金刚石,这些金刚石晶粒多分布于非晶碳中;继续升高退火环境气压则发现退火后样品被大面积氧化,石墨结构遭到严重破坏.该研究结果为纳米金刚石的制备提供了新方法.展开更多
碳化硅(SiC)电子器件的性能和成本受衬底质量影响,因此生长大直径高品质SiC单晶意义重大。物理气相传输(PVT)法是一种常用的生长方法,但其主要面临热场设计与气流控制问题。本工作对电阻加热PVT法生长150 mm SiC单晶完整过程开展数值仿...碳化硅(SiC)电子器件的性能和成本受衬底质量影响,因此生长大直径高品质SiC单晶意义重大。物理气相传输(PVT)法是一种常用的生长方法,但其主要面临热场设计与气流控制问题。本工作对电阻加热PVT法生长150 mm SiC单晶完整过程开展数值仿真研究,建立描述SiC原料热解和再结晶及其多孔结构演变、热-质输运、晶体形貌变化的数理模型,用数值模拟手段研究晶体生长、原料演变与热场变化等过程间的耦合关系。结果显示:原料区侧面高温导致气流不均匀,晶面呈“W”形,原料区底部高温得到均匀气流和微凸晶面;长晶界面通过径向温度变化调节气相组分平衡压力,使晶面生长成等温线形状;晶体生长速率与原料温度、剩余原料量呈正相关。模拟结果与已报道实验结果吻合,对优化生长SiC单晶有指导意义。展开更多
文摘超硬磨具激光增材制造过程中,金刚石极易受到激光直接辐照和高温熔池的影响,出现石墨化等热损伤现象.选取典型的金刚石磨具用金属结合剂CuSn10粉末,采用粉末床熔融(Powder Bed Fusion-laser Beam,PBF-LB)技术制备CuSn10-金刚石复合材料;围绕高能激光束和高温熔池两个影响增材制造过程中金刚石颗粒性能的关键因素,以单颗金刚石颗粒为研究对象,通过有限元模拟分析构建金刚石颗粒的温度场模型,反映了金刚石颗粒在PBF-LB中的热演化过程;阐明了PBF-LB过程金刚石的热损伤机制,发现金刚石发生石墨化转变并不是由激光的直接辐照造成的,而是由高温熔池的热影响导致,CuSn10-金刚石复合材料在PBF-LB过程中石墨化的临界温度为1491.6℃.建立了PBF-LB工艺-金刚石颗粒温度-石墨化程度-摩擦磨损性能的定量关系,发现随着金刚石颗粒温度的增加,其石墨化程度增加,严重损害了复合材料的摩擦磨损性能.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3608601).
文摘The ohmic contact interface between diamond and metal is essential for the application of diamond detectors.Surface modification can significantly affect the contact performance and eliminate the interface polarization effect.However,the radiation stability of a diamond detector is also sensitive to surface modification.In this work,the influence of surface modification technology on a diamond ohmic contact under high-energy radiation was investigated.Before radiation,the specific contact resistivities(ρc)between Ti/Pt/Au-hydrogen-terminated diamond(H-diamond)and Ti/Pt/Au-oxygenterminated diamond(O-diamond)were 2.0×10^(-4)W·cm^(2) and 4.3×10^(-3)Wcm^(2),respectively.After 10 MeV electron radiation,the ρc of Ti/Pt/Au H-diamond and Ti/Pt/Au O-diamond were 5.3×10^(-3)W·cm^(2)and 9.1×10^(-3)W·cm^(2),respectively.The rates of change of ρc of H-diamond and O-diamond after radiation were 2550%and 112%,respectively.The electron radiation promotes bond reconstruction of the diamond surface,resulting in an increase in ρc.
文摘碳化硅(SiC)电子器件的性能和成本受衬底质量影响,因此生长大直径高品质SiC单晶意义重大。物理气相传输(PVT)法是一种常用的生长方法,但其主要面临热场设计与气流控制问题。本工作对电阻加热PVT法生长150 mm SiC单晶完整过程开展数值仿真研究,建立描述SiC原料热解和再结晶及其多孔结构演变、热-质输运、晶体形貌变化的数理模型,用数值模拟手段研究晶体生长、原料演变与热场变化等过程间的耦合关系。结果显示:原料区侧面高温导致气流不均匀,晶面呈“W”形,原料区底部高温得到均匀气流和微凸晶面;长晶界面通过径向温度变化调节气相组分平衡压力,使晶面生长成等温线形状;晶体生长速率与原料温度、剩余原料量呈正相关。模拟结果与已报道实验结果吻合,对优化生长SiC单晶有指导意义。
