等离子表面冶金技术的现状与发展

双层辉光离子渗金属技术已成功地在普通碳钢表面形成高速钢、其中包括时效硬化高速钢、不锈钢以及镍基合金等；该技术已成功地应用于手用锯条和机用锯条，使其齿部形成高速钢，锯条不仅具有高速钢的切削性能，而且柔韧不断;钛合金表面经离子渗钼等工处理后，Ti6Al4V的耐磨性得到大幅度提高;经离子渗铌等工艺处理后，TiAl金属间化合物的抗高温氧化性能明显改善。在双层辉光离子渗金属技术的基础上，又发展了加弧辉光离子渗金属，双辉钎焊技术，双阴极辉光放电超硬薄膜合成技术，以及陶瓷表面金属化和异性材料焊接技术等。     

离子束表面冶金对高速钢表面性能的影响

本文介绍了用氮离子束轰击沉积在高速钢(W18Cr4V)表面上的铝膜,以改变高速钢表面合金成分的表面冶金技术;采用该技术处理高速钢后,高速钢表面的显微硬度和耐磨性得到较大提高。最后,讨论了由于氮和铝进入后引起高速钢表面机械性能变化的几个主要因素。     

多弧离子镀膜机(буиат-6)性能分析和工艺参数研究

分析研究了多弧离子镀膜机буиат—６的主要性能。在不同工艺参数条件下，于高速钢基体上制备了Ｔｉ膜和ＴｉＮ膜，用扫描电镜观察Ｔｉ膜表面形貌；用能谱仪对Ｔｉ膜上小液滴颗粒成份进行测试分析；用超微负荷硬度计测量了ＴｉＮ膜的显微硬度；用表面刻划仪测试了ＴｉＮ膜与基体的附着力。实验结果表明：选择适当的工艺条件，包括弧流大小，电磁场强度，镀膜时间以及冷阴极离子源辅助沉积，可获得性能优良的ＴｉＮ膜，其显微硬度可达Ｈｖ２５００，附着力为６５Ｎ。     

双辉等离子表面冶金技术的新进展

总结了近年来双层辉光离子渗金属技术的发展，介绍了以双辉工艺在钛及钛合金表面形成阻燃合金，采用无氢渗碳在钛及钛合金表面形成高硬抗磨层，在纯铁、碳钢等基材表面形成时效硬化高速钢，在纯铜表面形成Ti-Cu耐磨合金等表面冶金新技术。     

TiN涂层表面氧化层研究

在高速钢表面沉积ＴｉＮ涂层，运用ＳＥＭ，ＸＲＤ和ＸＰＳ等方法研究了ＴｉＮ涂层表面氧化物形成机理。结果表明，ＴｉＮ涂层表面氧化物为ＴｉＯ２，膜厚度约６０ｎｍ，系由涂层表面吸附氧而形成。     

强流脉冲离子束辐照对M2高速钢的表面改性

研究了强流脉冲离子束辐照对M2高速钢(W6M05Cr4V2)表面的微观组织和硬度的影响.结果表明,HIPIB辐照处理使高速钢样品表面强烈加热又快速冷却,产生表面淬火作用,导致碳化物溶解,马氏体溶碳量增大且晶粒细化或晶格畸变度增大,晶间出现残余奥氏体.辐照还使表面产生宏观残余压应力,形成一些弥散分布的火山口状熔坑.随着脉冲次数的增加,在材料表面产生微区光化现象,材料表面化学成分和相组成的差异、杂质分布以及位错密度不均匀性导致的非均匀、非稳定熔化等是产生熔坑的主要原因.辐照使材料表层及以下近200μm范围内的硬度提高,并出现硬度双峰现象,离子束辐照产生的应力波及其在材料中的传播所导致的位错密度增大是硬度提高的原因.     

MoS2软涂层刀具的基体材料优选及涂层制备

以常见的几种高速钢和硬质合金为基体材料，运用有限元软件分析了基体表面MoS2软涂层的残余热应力。结果表明：高速钢表面涂层的最大残余热应力小于硬质合金表面涂层的残余热应力；涂层与基体之间弹性模量和热膨胀系数等参数及沉积温度的差异是影响涂层残余热应力大小的主要因素。采用中频磁控溅射加离子束辅助沉积工艺制备了两种MoS2软涂层刀具并对其性能进行了测试，分析结果符合有限元计算的结论。     

电弧离子镀TiN及其复合膜的腐蚀机理探讨

利用电弧离子镀在高速钢基体上制备了TiN及其复合膜（Ti，Cr）N，通过盐水全浸泡试验测量了薄膜的腐蚀速率。利用SEM观察了薄膜腐蚀后的表面形貌及断口形貌，并用其自带的能谱分析仪测量复合膜中Cr的含量，讨论了带有宏观熔滴颗粒的TiN及其复合膜（Ti，Cr）N的腐蚀机理。结果表明：高速钢表面电弧离子镀TiN和（Ti，Cr）N复合膜均可提高其耐腐蚀性能，薄膜的腐蚀主要有小孔腐蚀、缝隙腐蚀及电偶腐蚀。     

M2高速钢表面脉冲爆炸-等离子体改性后的组织结构及性能

为进一步提高高速钢工模具的性能,首次利用脉冲爆炸-等离子体(PDT)技术对M2高速钢进行了表面改性,利用SEM、XRD分析了M2高速钢经PDT处理前后的表层组织和相结构,采用显微硬度计、摩擦磨损试验机及极化曲线研究了M2高速钢经PDT处理前后的显微硬度、耐磨性能和耐蚀性能。结果表明:PDT处理使M2高速钢表层发生马氏体α’-Fe向奥氏体γ-Fe的相转变过程,随着PDT处理脉冲个数的增加,奥氏体含量增加,且部分碳化物固溶于奥氏体中;经PDT处理后,M2高速钢表面形成平均厚度为8.9μm的改性层,改性层组织细小致密,碳化物颗粒细小且分布均匀;在PDT处理过程中的爆炸冲击产生的高温高压作用下,高速钢表层在深度达100μm范围内显微硬度得到提高,耐磨性能最多提高了2.3倍,耐腐蚀性能也明显改善。     

新型高速钢及表面热处理的发展现状

高速钢是最重要的工具材料之一。综述了新型高速钢及表面热处理的研究和发展现状,着重分析讨论了新型低合金高速钢,超硬高速钢,高速钢基复合材料,以及激光表面热处理和ＰＶＤ涂层技术的现状及发展趋势。     

圆锯片振动频率的控制方法

中心夹持高速旋转的圆锯片切削工件时,保持良好的切削稳定性是非常重要的.目前提高锯片切削稳定性的方法有研究新的锯片材料、改善材料性能、改变锯片的结构和几何参数、改变齿形和对锯片进行适张度处理等,对圆锯片采用胀孔适张度处理,在锯片上均布加工一些孔,然后在孔中压入圆锥塞,使之在锯片内产生残余应力场,残余应力场的存在提高了锯片的固有频率,减少锯片的横向振动,从而增加了锯片切削的稳定性.     

Optimizing the performance of high speed steel circular saw blades machining cupro 107, Inconel 600L and Nimonic PK31 nickel based alloys

Nickel based alloys are machined by methods similar to those used to cut ferrous materials, however there are additional process requirements due to the poor machinability of these alloys. The current paper reports on work undertaken to optimize the cutting conditions for high speed steel circular saw blades machining materials from three of the principal categories of nickel based alloy.Techniques have been developed and verified that simulate the cutting characteristics of multi-point cutting tools by testing blade segments that contain representative teeth. The cutting behaviour of high speed steel circular saw blades have been simulated in this manner. Materials from three of the principal classifications of nickel based alloy; Cupro 107, Inconel 600L and Nimonic PK31, have been machined over a range of cutting feeds and speeds. Cutting and thrust forces were measured and the performance criteria, specific cutting energy (Esp) evaluated. Optimized cutting conditions for each material were determined from curves of Esp against feed rate at the selected cutting speeds.In an area of high product and material costs, the information contained within this paper will be of interest to the manufacturing engineer and end user when appraising the suitability of high speed steel circular saw blades as a tool for machining these materials.Inconel 600L and Nimonic PK31 are registered trademarks of the Inco Family of Companies.     

LASER HARDENING OF TURBINE BLADES

This paper briefly describes our theoretical and experimental work on the laser heat treatment of the surfaces of martensitic stainless steel turbine blades. A hardened zone, very small in thickness compared to the blade, has been obtained without melting the substrate or reducing its hardness. A large spot with a high density power (as calculated by ad hoc thermal models) was necessary to treat each blade in a single pass; consequently a high power (15 kW) laser was used. Good metallurgical results were obtained with a total absence of cracks, porosity or other defects.     

钛铝低压涡轮叶片熔模铸造精确成形及冶金缺陷分析

目的 研究不同浇冒口设置对TiAl低压涡轮叶片的成形的影响及叶片冶金缺陷形成的原因。方法 采用熔模精铸方法,通过设计顶注式重力铸造浇注系统,采用冷坩埚感应熔炼炉进行TiAl叶片浇注实验,采用目视和X射线检验方法分析叶片铸件表面及内部缺陷,并结合金属凝固理论分析缺陷形成原因。结果 合理的浇口和排气孔设置有效避免了因熔体流动性差造成的叶片充型不完整,以及凝固收缩导致的应力开裂等问题,浇注出成形完整的铸造叶片;叶冠与叶身端部转角部位充型凝固过程中形成热节,容易出现贯穿性疏松缺陷;树脂基熔模焙烧后残留的碳黑在熔体充型凝固过程中,与面层中的ZrO2反应生产CO,导致叶身出现聚集性皮下气孔;由于凝固收缩引起叶身与铸型分离,降低横向散热能力,导致叶盆部位出现表面疏松。结论 通过浇注合理的浇注系统设置可实现TiAl叶片完整充型,疏松缺陷控制为进一步提高叶片质量的关键。     

Failure of Low-Pressure Turbine Blades in Military Turbofan Engines: Causes and Remedies

Failure of low-pressure (LP) turbine rotor blades in low bypass military turbofan engines is a great concern for designers, manufactures, repair and overhaul agencies, operators, and airworthiness authorities. The present paper analyzes the LP turbine blade failure cases to determine its root cause. Forensic and metallurgical investigations are carried out on the failed blades. In most cases, the failure was originated from the leading edge and had propagated toward the trailing edge. Intergranular features and high oxidation on the fractured surface have been found as the cause of fatigue failure. Operation at elevated temperatures for considerable time was found responsible for these fatigue failures. Malfunction of fuel system, failure in control sensors, and nonuniformity in atomizer characteristics were the root cause of high temperature in turbine leading to the failure of blades. The paper also presents various remedial measures to address the blade failures from manufacturing and operational points of view.     

20CrV钢机用锯条齿部表面强化组织的研究

本文介绍了２０ＣｒＶ钢机用锯条经渗金属、渗碳、淬火及回火的表面强化处理工艺，并对强化后锯条齿部碳化物、相结构进行了组织分析和Ｘ射线检测。研究结果表明，齿部组织状态及相结构已接近高速钢，经切削试验，性能达到高速钢要求。     

GFRP复合材料叶片摆振运动表面位移与层间断裂韧性响应

风机GFRP复合材料叶片摆振运动时产生的层间滑动裂纹是叶片破坏的主要诱因之一,应力强度因子K是层间断裂韧性的重要参量,也是表面裂缝安全性评估的重要指标之一。本文在试验基础上提出了由GFRP复合材料叶片表面位移推导K值的新方法,通过试验验证其理论正确性,试验与仿真对比证明了通过叶片摆振运动表面位移来研究层间断裂韧性响应的方法是可行的,为GFRP复合材料风机叶片的强度预测提供了新的思路和方法。     

大型水平轴风力发电机桨叶稳定性研究

大型水平轴风力发电机桨叶为流-刚-柔耦合的周期时变多体系统。本文暂未考虑风载荷,分析了重力载荷和桨叶预锥角、转速等因素的变化对稳定性的影响。力学建模中,考虑了桨叶挥舞、摆振、扭转和轴向运动以及根部铰的挥舞、摆振和变矩等刚体运动。利用有限元法形成5节点18自由度的刚-柔混合梁单元模型,应用Hamilton原理建立桨叶动力学方程,求得对应的摄动方程,采用Newmark隐式积分方法求解。根据Floquet理论判断运动稳定性,计算了相关转换矩阵的特征值。结果表明预锥角对桨叶运动稳定性影响不容忽视。在通常的工况下,桨叶能够稳定地运转。     

Failure of last-stage turbine blades in a geothermal power plant

This paper presents an investigation into causes of failure of geothermal steam turbine blades. Several L-0 blades of geothermal steam turbines of 110 MW capacity suffered failures, causing forced outages of the turbines. To assess the causes of failure, the natural frequencies of the blades installed on the rotor were measured in the laboratory. The measured frequencies were compared with the natural frequencies calculated through a finite-element analysis (FEA) of the blade. The FEA was also used to calculate the vibratory stresses on the blade numerically. Also, the investigation analyzed the operational data and the history of the blade failures on several rotors of different units from the same system. The results of previous repairs were reviewed, and metallurgical investigations were conducted to identify the mechanical and metallurgical modes of failure. The results of the investigation showed that the fracture of two blades was attributed to installation and manufacturing errors and aggravated by general deterioration of the blades. The deterioration was caused by the erosion and corrosion process that resulted from moisture condensation in the steam.