金刚石孔钻连续炉钎焊工艺研究

通过在连续炉钎焊炉中对金刚石进行钎焊试验,并用所制得的金刚石孔钻进行钻削试验,得到了批量生产金刚石孔钻的可行钎焊工艺。利用扫描电镜比较了金刚石磨粒分别在真空钎焊和网带炉钎焊后的不同形貌,建立了孔钻的有限元模型,并模拟计算出孔钻在钎焊炉中的热循环曲线。对比热电偶实测结果,验证了有限元模型的准确性,对比分析了真空钎焊工艺和连续网带炉钎焊工艺的异同及其对孔钻使用寿命的影响。     

钎焊气氛对金刚石磨耗特性的影响

采用NiCr合金钎料,通过Ar气保护和真空钎焊的方法制备了钎焊金刚石耐磨性试件,并研究了钎焊气氛对金刚石磨耗特性的影响。结果表明：在试验条件完全相同的情况下,不同的钎焊气氛导致金刚石磨耗特性不同,即经真空钎焊金刚石的磨耗特性表现为破碎方式,而经Ar气保护炉中钎焊金刚石的磨耗特性初始表现为磨耗平台方式,其后随着磨耗平台面积的增大,金刚石出现破碎。最后采用Ar气保护和真空钎焊方式制作了金刚石套料钻并进行了钻削试验,由于磨耗特性的不同,Ar气保护炉中钎焊套料钻较真空钎焊套料钻具有更长的使用寿命。     

碳碳复合材料快速沉积炉石墨加热系统设计

本文以开发的碳碳复合材料快速沉积炉为依托,详细介绍碳碳复合材料快速沉积炉(CVI:Chemical Vapor Infiltration)石墨加热器的设计过程,根据设备和工艺使用要求,重点介绍加热保温系统中的加热器设计、加热器表面负荷校核、加热器应力校核。实验结果表明:所设计的石墨加热器满足生产工艺要求;项目在实际生产过程中取得了1mm/h的碳沉积速度;产品在硅单晶炉热场使用中达到了预期使用寿命,成本价与同规格石墨价格接近,满足使用要求。     

液冷壳体真空钎焊工装的结构优化

通过对液冷壳体真空钎焊工装的研究,在保证工装设计安全裕度在可靠范围内的前提下,以减少液冷壳体真空钎焊工装的质量、提高液冷壳体的真空钎焊装炉量为目的,通过三维模型建立、结构分析及有限元仿真分析,对真空钎焊工装的主要结构进行优化,达到了工装减重的目的,为提高液冷壳体的真空焊接装炉量提供理论支撑.     

多层级冗余控制系统在热处理真空钎焊炉中的应用

自20世纪80年代以来,真空钎焊炉控制系统先后经历了仪表控制时代、PLC控制时代、DCS控制时代。随着真空钎焊炉的大型化发展,钎焊产品价值的提高,其控制系统的自动化、集成化程度的提升,对整个控制系统的可靠性提出了越来越严格的要求。为此,基于西门子的S7-400H多层级冗余控制系统应运而生。大型钎焊炉的多级冗余控制系统构成包括:底层I/O通道冗余,CPU控制器冗余,网络冗余,监控计算机冗余。这种多层级冗余系统在国内大型真空钎焊炉中的应用尚属首例。大型钎焊炉的控制系统按功能主要分为温度系统控制和真空系统控制。温度控制系统打破了传统的仪表控制+PLC控制模式,采用基于西门子S7-400H的集成一体化控制,实现了数字量控制与模拟量控制的完美结合。真空系统控制为分阶段分部自动控制模式,这种模式在大型钎焊炉控制系统中优于全自动和手动模式。相对于全自动模式来说,其优点是故障处理的能力提高了,进行分部分阶段的控制,对设备的维护、工艺进程故障处理具有极大的好处。对于纯手动控制系统来说,简化了操作的工业流程。降低了人为操作的失误率。在大型钎焊炉中控制系统中得到了很好的应用。     

钎焊气氛对金刚石钎焊性能的影响

主要利用Cu-10Sn-5Ti钎料粉末,在空气、Ar气保护和真空气氛下分别对金刚石进行钎焊试验,通过扫描电子显微镜观测金刚石钎焊形貌、X射线衍射仪分析界面生成物成分、激光拉曼光谱仪检测金刚石石墨化程度、磨损试验分析金刚石破损形式等手段,考察研究不同钎焊气氛对金刚石钎焊性能的影响。试验结果表明,在空气中钎焊时,钎料粉末出现了一定的氧化,生成的氧化膜阻碍了界面反应的充分进行,对钎焊性能有一定的影响,金刚石也出现了较严重的热损伤,磨削过程中出现了少数部分颗粒脱落的情况;而在Ar气保护和真空钎焊时,钎料充分润湿和铺展,实现了对金刚石的高强度把持,金刚石石墨化程度很小,金刚石主要经历了完整、小块破碎、大块破损、磨平等正常磨损形式,金刚石利用率高。     

稀土铝锂合金钎焊性研究

从界面活性、钎合率和最佳钎缝间隙等方面对２０９０Ｃｅ铝锂合金的真空钎焊和炉中钎焊进行了比较性研究，为这种新型轻金属结构材料的钎焊应用提供了基础。     

Ag-Cu-Ti活性钎料真空钎焊钨、石墨与铜的研究

研究了Ag-Cu-Ti活性钎料高真空钎焊钨与铜与石墨与铜，结果表明，钎焊钨与铜时可获得接近母材铜强度的接头，剪切断裂发生在铜与Ag-Cu-Ti之间的扩散层中，钎焊石墨与铜时接头最大强度为32MPa，剪切断裂主要发生在近石墨与钎缝金属界面的石墨中，高强度结合界面是通过活性元素Ti向钨或石墨扩散并与之反应而形成的。     

ZR－1416－8真空钎焊炉电气控制系统

本文简要介绍了真空钎焊炉的构造及其电气控制系统的运行机理。     

ZR—1416—8真空钎焊炉电气控制系统

本文简要介绍了真空钎焊炉的构造及其电气控制系统的运行机理。     

A Vacuum High-Temperature Electric Furnace for Investigating Thermal Properties of Materials

A vacuum electric furnace for investigating thermal properties of materials at temperatures of up to 2500°C was developed and tested. The furnace allows experimental studies of the heat conduction of both liquid and solid materials and measurements of the temperature and heat of phase transitions. It can be used to smelt and cake metals and alloys in vacuum or in an inert-gas medium. The heater is made of a graphite tube with special slots for increasing its resistance. The electric power is supplied from an ОСУ-40 step-down transformer. The temperature in the heated zone is controlled and monitored with an РТЭ-4.1 digital temperature controller connected to a computer. The power consumed by the furnace is no higher than 20 kW, and the volume of the working chamber is 0.3 L. The time for reaching the maximum temperature is at most 30 min.     

EDM石墨电极快速研磨成型研具的开发研究

简介Hauseman研磨研具的特点、制造要求和制造方法;对研具配方进行深入的理论分析,在此基础上,通过实验获得研具制造的最佳配方,并进行了研磨实验给予验证。     

球化孕育处理工艺对下贝氏体铸铁组织特性及力学性能的影响

采用真空中频感应炉,通过改变球化孕育处理工艺获得具有不同形态石墨的铸造试样,将铸件加热到860 ℃保温2 h,使用20 ℃的硝酸钠、亚硝酸钠饱和溶液将其连续冷却至室温,并在250 ℃低温回火2 h后空冷,获得具有不同形态石墨的下贝氏体基体组织。研究了球化孕育处理工艺对石墨球化效果的影响,以及石墨形态对热处理显微组织和力学性能的影响。结果表明：球化处理温度及时间对铸铁中的镁吸收率有显著影响,超过1 500 ℃时,镁烧损加剧,当球化处理温度为1 450 ℃,镁吸收率达到64.2%;孕育剂添加工艺也是影响铸铁中石墨的形态和分布的重要因素,当一次孕育和二次孕育添加量分别为0.8%和1.2%时,石墨的形态以球状为主,尺寸细小且分布均匀,石墨的球化率为93%,球化级别达到2级,尺寸级别为9级;另外,均匀分布的球状石墨有利于提高热处理后下贝氏体铸铁的综合力学性能。     

用Hauseman方法研究EDM石墨电极研具的磨损与堵塞问题

理论与实验相结合的方法，深入研究EDM石墨电极Hauseman研磨研具的磨损与堵塞问题。首先分析研具磨损的形式和机理、研具堵塞的类型和形貌，接着分析研究影响研具堵塞的因素，最后提出改进措施。     

Manufacture of graphite electrodes for the electrospark machining of complex high-precision components

The manufacture of complex graphite electrodes for electrospark broaching is considered. Recommendations are made regarding the milling of graphite, and the design features of the electrodes are shown for a specific example.     

两种钎焊金刚石工具微观结构的对比分析

分别利用真空电阻炉中钎焊和氩气保护下高频感应钎焊制作单层钎焊金刚石工具,借助SEM、EDS和XRD等分析了两种工具的微观结构。结果表明：电阻炉中钎焊的金刚石一钎料界面上有两层结构,内层产物是Cr3C2,外层产物是Cr7C3;高频钎焊的金刚石一钎料界面上仅有单层产物Cr3C2。这两种工艺制作出来的工具,其界面结构虽有差别,但都存在化学冶金结合,足以保证金刚石和钎料层之间具有较高的结合强度。     

MoS2/石墨溅射涂层在真空中不同载荷下的摩擦磨损行为研究

为改进纯MoS2涂层的耐磨损性能,采用溅射技术合成了添加石墨的MoS2涂层。在球-盘摩擦试验机上,考察了法向载荷对MoS2/石墨溅射涂层真空中的摩擦因数和磨损率的影响,并利用扫描电子显微镜对其磨损形貌进行了分析。结果表明:在真空条件下,涂层的摩擦因数随着法向载荷的增大而减小;磨损率随载荷的增加而增加。涂层在真空中较低载荷下的磨损机制为疲劳磨损;在较高载荷下的磨损主要由塑性变形引起的小板片磨损控制。     

Study on erosion mechanism of graphite electrode in two-electrode spark gap switch

In a high-powered single pulse system, the graphite electrode is better than other common metal electrodes for high energy transfer and pulse discharge. In this paper, the erosion mechanism of graphite electrode is investigated with the thermodynamics theory and the experimental results. Based on a simplified mathematical model, the graphite electrode erosion process of high-powered spark gap switch is also analyzed. The analysis results show that the relationship of the graphite electrode erosion and the charge transfer is linear, which is accordant with the experimental results.     

Effect of electrical current on the tribological behavior of the Cu-WS2-G composites in air and vacuum

As the traditional graphite-based composites cannot meet the requirement of rapid developing modern industry, novel sliding electrical contact materials with high self-lubricating performance in multiple environments are eagerly required. Herein a copper-based composite with WS2 and graphite as solid lubricant are fabricated by powder metallurgy hot-pressed method. The friction and wear behaviors of the composites with and without current are investigated under the condition with sliding velocity of 10 m/s and normal load of 2.5N/cm 2 in both air and vacuum. Morphologies of the worn surfaces are observed by optical microscope and compositions of the lubricating films are analyzed by XPS. Surface profile curves and roughness of the worn surfaces are obtained by 2205 surface profiler. The results of wear tests show that the friction coefficient and wear volume loss of the composites with current are greater than that without current in both air and vacuum due to the adverse effects of electrical current which damaged the lubricating film partially and roughed the worn surfaces. XPS results demonstrate that the lubricating film formed in air is composed of oxides of Cu, WS2 , elemental S and graphite, while the lubricating film formed in vacuum is composed of Cu, WS2 and graphite. Because of the synergetic lubricating action of oxides of Cu, WS2 and graphite, the composites show low friction coefficient and wear volume loss in air condition. Owing to the fact that graphite loses its lubricity which makes WS2 become the only lubricant, severe adhesive and abrasive wear occur and result in a high value of wear rate in vacuum condition. The formation of the lubricating film on the contact interface between the brush and ring is one of the factors which can greatly affect the wear performance of the brushes. The low contact voltage drop of the composites in vacuum condition is attributed to the high content of Cu in the surface film. This study fabricated a kind of new sliding electrical contact self-lubricating composite with dual-lubricant which can work well in both air and vacuum environments and provides a comprehensive analysis on the lubrication mechanisms of the composite.