内燃机活塞环表面处理技术

活塞环在内燃机中有着支撑、密闭、储油、导热的作用,内燃机活塞环制备材料应该具备优良的加工性能、耐高温、耐腐蚀、导热性好且具有良好的强韧性,较好的与气缸材料表面的磨合性能。球墨铸铁和专用钢材已经成为制备内燃机活塞环的基础材料,目前国内外采用多种表面处理技术比如:镀铬、氮化、PVD与CVD镀膜、喷钼、喷涂陶瓷层等表面处理工艺进行表面改性,提高内燃机活塞环的使用寿命和使用性能。需要不断研究和开发新的内燃机活塞环的表面处理技术来满足实际生产和应用中内燃机越来越高的要求。     

NiTi形状记忆合金激光气体氮化层表面特征

为改善NiTi合金的表面性能，利用2kW连续波Nd：YAG对NiTi合金进行激光气体氮化处理。采用SEM、TEM、XRD、XPS和纳米压痕研究了氮化层的显微组织及表面特征．结果表明：激光气体氮化可以在NiTi合金表面制备连续、无裂纹、厚度为2μm的TiN表面层，该表面层中基本不合有Ni元素且具有很高的硬度，其纳米压痕硬度为29．28GPa．     

激光相变硬化对离子渗氮层的影响

采用ＸＰＳ研究了３５ＣｒＭｏ钢离子氮化加激光相变硬化复合处理后不同层深处氮的变化。结果指出，复合工艺可在表层获得更深的氧氮化物层，含氮层的深度也将加大，并且与原渗氮层相比可在更深的位置得到氮化物层。     

基于L298N芯片对离子渗氮中压强的控制

离子渗氮工艺对炉体内压强的控制要求比较高，本文设计了一种基于L298N芯片驱动直流电动机控制的气体流量控制器，可用于控制反应炉的抽气气体流量，提高了炉体压强控制精度，降低了生产成本。     

Tribology of nitriding layer, TiN coatings and their complex on AISI D2 steel

The sliding wear and impact wear resistances of D2 steel with nitriding layer, PVD titanium nitride coating and their duplex treatment were investigated. The experimental results suggest that the duplex treatment has the best sliding and impact wear resistances under experimental conditions. And the wear resistance of PVD titanium nitride is better than that of nitriding. The impact wear resistance and wear mechanism of all three surface layers remain unchanged under impact load of 0.2 J or 1 J. All samples end with the same symptom of flaking.     

离子氮化对镀铬层组织与性能的影响

研究了镀铬层经离子氮化后的组织和性能。分别用SEM、电子探针和X光衍射仪观察和分析了复合处理层剖面的组织、结构和成分,试验结果表明:离子氮化能使镀铬层的网状裂纹弥合,可明显提高了镀层表面硬度、结合力和耐蚀性。     

取向硅钢氧化膜结构对渗氮层深度的影响

摘要：低温板坯加热技术生产取向硅钢,其关键点之一在于脱碳退火后要进行渗氮处理。通过控制脱碳气氛,获得不同的氧化膜结构;并进一步分析在近似渗氮量条件下,氧化膜结构对渗氮层深度的影响。结果表明：氧化膜分为外层颗粒状氧化膜和内层层片状氧化膜两部分。随着脱碳气氛露点增加,脱碳板O含量增加,氧化膜厚度增厚、层片状氧化膜占氧化膜总厚度的比例下降,渗氮层深度增加。当层片状氧化膜厚度占比较高时,［N］原子积聚在试样的极表层,形成氮沿厚度方向的单峰分布,渗层较浅。当层片状氧化膜厚度占比较低时,［N］原子会越过该层,而在次表层再次发生积聚;从而除了极表层的氮峰外,在次表层形成一个或多个氮峰,渗层较深。     

The internal nitriding behavior of Co-3Cr,Co-3Al,and Co-3Ti (a/o) over the range of 700–1100°C

Internal nitridation of Co containing 3 a/o of either Cr, Al, or Ti was studied over the range of 700–1100° C in NH₃/H₂ (694 ratio). The kinetics of thickening of the reaction zone followed the parabolic rate law, suggesting that solidstate diffusion was rate controlling. Activation energies obtained were 51.2 Kcal/molfor Co-3Cr, 46.6 Kcal/mol for Co-3Ti, and 27.9 Kcal/mol for Co-3Al. XRD showed only CrN, AlN, and TiN. Deep etching revealed that AlN formed hexagonal plates near the surface when formed at high temperature, the precipitates becoming more massive (blocky morphology) near the reaction front. TiN formed elongated dendritic precipitates, whereas CrN tended to form spheroids. The precipitate size varied with temperature, decreasing with decreasing temperature. In some cases, nitriding formed a case but no visible precipitates even at very high magnifications in the SEM. The solubility of nitrogen in cobalt was determined by long-time equilibration and subsequent chemical analyses. The diffusivity of nitrogen in cobalt was determined from measured permeabilities and the experimentally determined solubilities. Mechanisms are discussed, and the behavior of internal nitridation is compared with internal carburization and oxidation in cobalt alloys.     

表面强化件的疲劳强度分析及金属的内部疲劳极限

本文通过对喷丸，渗氮及碳氮共渗试样疲劳行为的研究，提出了金属内部疲劳极限的概念，指出内部疲劳极限约为表面疲劳极限（一般意义上的疲劳极限）的１．３５倍，并利用这个概念分析了表面强化件的疲劳强度。     

盐浴硫氮碳共渗45钢的接触疲劳性能

对４５钢经盐浴硫氮碳共渗处理的大批试样，进行了滚子接触疲劳性能试验，绘出了Ｐ－Ｓ－Ｎ曲线，分析了接触疲劳断口形貌及破坏机理。