WC／Cu复合材料粉末冶金烧结工艺研究

通过压制压力、烧结温度和烧结时间对ＷＣ／Ｃｕ压坯组织和性能的影响,研究了粉末冶金颗粒增强复合材料的烧结特点、确认了ＷＣ颗粒对烧结的阻碍作用,认为ＷＣ／Ｃｕ压块不能通过简单烧结来达到致密化。     

粉末冶金汽车零件的新进展

作者陈述了汽车工业中粉末冶金零件的最近进展情况,在汽车制造中,铁基烧结零件是大有用处的,如烧结锻造连杆,粉末冶金凸轮轴等等。本文还介绍了粉末冶金的新技术和新材料。     

粉末冶金零件加工研究进展

介绍了国内外粉末冶金烧结件加工的研究现状,对工艺参数优化、刀具磨损、已加工表面质量进行了详细分析,阐述了改善粉末冶金烧结件可加工性的措施:表面浸渗、添加易切削剂。分析了粉末冶金生坯加工时工艺参数对已加工表面质量的影响、生坯强度的提高以及生坯加工后的烧结件的力学性能。     

铁基粉末冶金材料的合金化与热处理

为了提高粉末零件的机械性能,目前在铁基粉末冶金材料中往往加入合金元素,通过活化烧结来实现合金化,以便提高密度、强度和控制烧结体的尺寸变化。随着粉末冶金技术的不断发展,广泛使用雾化预合金粉以及粉末锻造工艺以后,出现了高密度高强度烧结锻钢,提高了性能并扩大了应用范围。铁基粉末冶金材料的合金化与热处理也获得了重视。     

弥散粒子对铜粉烧结抑制作用的探讨

本文以Cu-0.86V%Al_2O_3球形粉、相对密度92%的压块进行烧结试验,研究了氧化铝粒子对烧结过程的抑制作用。并对烧结机理、烧结温度和时间的影响进行了讨论。认为弥散铜粉压块不能通过简单烧结达到完全致密化。     

铁基和铝基粉末冶金新材料的动向

近年来,通过开发更加新型的粉末制造技术及加工技术,已能开发具有用以往技术所得不到的优良特性(诸如强度、韧性及耐热性等)的材料,并已开始探讨应用于飞机制造工业。本文简述铁基和铝基粉末冶金材料的发展动向。一铁基粉末冶金新材料用于汽车、电机及办公仪器等机械零件为中心的粉末冶金法,是一种适于大量生产、经济效益高等特点的零件加工技术,目前用于生产的零件产量已大大地增加。表1是一般烧结机械零件材料的机械特性.目前正通过新型的粉末制造、烧结技术及加工技术,近来开发了如表2所示的Ni-Mo 系,Mn-Cr 系的高强度烧结钢,已达到了实用化阶段。尽管在这些烧     

工农-10型小型拖拉机末端传动主齿轮粉末冶金热锻的研制

粉末冶金热锻是采用普通粉末冶金方法,将金属或合金粉末制成一定尺寸、形状和重量的予成形坯,经过烧结,然后加热锻造(简称烧结锻造)或者不经烧结而直接加热锻造(简称粉末锻造)成产品形状。粉末冶金热锻工艺吸取了锻造工艺的特点,通过加热锻造的途径,大大提高了粉末冶金制品的密度,从而使粉末冶金制品的性能提高到接近甚至超过同类锻钢的水平,从根本上克服了普通粉末冶金制品由于存在大量的孔隙,而满足不了高强度零件性能要求的缺陷。然而,粉末冶金热锻又不同于普通致密钢的锻造,它保持了粉末冶金工艺的特点。多孔粉末冶金予成形坯,一     

粉末冶金齿轮的齿型计算和最佳圆角

应东莞某厂之约，研究了粉末冶金齿轮的齿型计算和最佳圆角。与切削加工的齿轮不同，需要研究烧结齿轮的模腔的数控线切割机加工时镍丝的运动轨迹，又为齿根圆角的形成提供了修改的自由度，有利于提高粉末冶金硬质合金烧结齿轮的弯曲强度。     

石油射孔弹粉末冶金易碎弹壳的研制

主要介绍一种石油射孔弹粉末冶金易碎弹壳,采用粉末冶金技术工艺,解决了材料配方选择、自动成型、气氛烧结和后续水蒸汽处理等技术难题,确保了弹壳形状、机械强度,达到了穿深技术指标和特殊的破损性能,取得了一项技术发明专利。     

铜基粉末冶金材料—钢背结合界面的研究

为了节约铜基粉末冶金材料,以及增强铜基粉末冶金材料的强度,可以把铜基粉末冶金的坯料烧结在钢的底板上(或用其它方法焊接在钢板上)。为了使烧结过程能顺利有效地进行,S.K.Wellman公司提出了在钢底板上预先电镀一层约25μm的铜。这一方法直到现在还在被广泛地采用,我国有关生产单位也是采用这一方法的。由于铜基粉末冶金材料不能与钢底板形成良好的冶     

机械合金化改性硫化亚铁/铜合金粉末的特性

为了解决FeS/Cu粉末冶金复合材料中FeS易团聚以及界面结合差的问题,采用机械合金化技术制备了FeS/Cu复合材料粉末。利用扫描电镜、X射线衍射仪、金相显微镜等对不同球磨时间的质量分数为6%的FeS/Cu合金粉末的混合特性、压制特性及烧结后的力学性能进行检测和分析,结果表明：机械合金化可有效改善FeS颗粒与基体合金粉末的混合均匀性,烧结后材料的密度、硬度均得到提高,FeS和Cu界面结合良好;由于FeS颗粒均匀弥散地分布在铜合金基体中,割裂了基体材料的连续性,反而使复合材料的韧性和压溃强度有所降低。     

Ni和Fe对Cu-Sn-P系粉末冶金轴承材料性能的影响

在Cu-Sn-P系基体中添加不同量的合金元素N i和Fe,采用粉末冶金方法制备烧结轴承材料,通过对比研究了N i和Fe对其性能的影响规律。结果表明,N i和Fe元素都可以提高材料的表观硬度和压溃强度,改善材料的摩擦磨损性能,但N i元素对压溃强度的提高更为显著。Cu-Sn-P基体中添加N i和Fe含量不宜过高,分别以2%和4%为宜。     

Research on manufacturing Cu matrix Fe-Cu-Ni-C alloy composite parts by indirect selective laser sintering

The property of alloy parts can be adjusted conveniently if alloy element powders are used for manufacturing alloy parts by indirect selective laser sintering (SLS), but there have been no reports in this field. Fe, Cu, Ni, C composite powders of two compositions were obtained through a 3D blending way in this paper. Green parts of above composite powder were manufactured by indirect SLS. Then, Cu matrix Fe-Cu-Ni-C alloy composites were produced after green parts had been depolymerized, high temperature sintered and infiltrated by molten Cu. The post-processing of green parts, microstructure and mechanical properties of alloy composites were investigated. The results show: Ni, Cu and C diffuse into γ-Fe when green parts are being sintered at high temperature and the distributing non-uniformity of alloy elements is eliminated basically; at room temperature, alloy composite microstructures are composed of lower bainite, α-Cu precipitated out of γ-Fe and Fe-Ni after they have been solution treated at 930°C and held at 350°C for 1 h later; the yield strength of alloy composites is near to 400 MPa and the elongation is under 3%. It can be used for manufacturing injection mold or other functional parts by indirect SLS.     

高压共轨喷油器测试电路设计及其检测平台开发研究

为了检测高压共轨喷油器的工作性能,改善汽车尾气的排放质量,对高压共轨喷油器的动作原理及其检测波形进行了分析,并对喷油器的喷油量进行了计算。采用PLC技术,利用PWM方法,设计了一种喷油器检测电路及其测试平台,可以检测各类型号的高压共轨喷油器在怠速及全油门状态下的喷油状况,对其喷油质量给出判定,该平台也可进行喷油嘴驱动电路的优化研究。     

电控喷油器强度的有限元计算分析

喷油器是电控喷油系统中最基本、最关键的元件之一,它接受电子控制单元（ECU）发出的控制指令,完成喷油过程,以实现满足系统要求的各种不同喷油规律。由于喷油器的工作油压很高,为保证其工作的安全性和可靠性,检验其结构参数是否合理,有必要对其进行有限元强度计算。本文采用大型CAD软件I-DEAS Master SeriesTM,对喷油器体进行了强度计算和应变分析。对喷油器的结构参数和材料选择进行了调整和优化,为喷油器的结构设计和材料选用提供理论指导,提高设计成功率,降低开发成本。     

Sliding wear behavior of copper alloy contact wire against copper-based strip for high-speed electrified railways

This paper reports the study of the sliding wear behavior of the Cu–Ag–Cr wire. Cu–Ag–Cr alloy is a promising contact wire material for high-speed electrified railways, which has an excellent combination of mechanical strength and electrical conductivity. Wear tests were conducted under laboratory with a special sliding wear apparatus, which simulated the tribological conditions of sliding current collectors on overhead wires in the railway system. The Cu–Ag–Cr alloy wire was slid against a copper-based powder metallurgy strip under unlubricated conditions. The same strip as those in the train systems were used. Worn surfaces of the Cu–Ag–Cr alloy wire were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDS). Within the studied range of electrical current, normal pressure and sliding speed, the wear rate increased with the increasing electrical current and the sliding distance. Compared with a Cu–Ag contact wire under the same conditions, the Cu–Ag–Cr alloy wire had much better wear resistance. Adhesive wear, abrasive wear and arc erosion were the dominant mechanisms during the electrical sliding processes.     

Microstructural evolvement and formation of selective laser melting W–Ni–Cu composite powder

W–Ni–Cu alloy (90 wt% W, 7.5 wt% Ni, and 2.5 wt% Cu) parts were successfully fabricated via selective laser melting method. Phases, microstructure, compositions, and laser forming parameters of laser melted samples were investigated. It was found that the W–Ni–Cu powder system was based on the mechanism of liquid solidification. This process was realized through full melting of W, Ni, and Cu particles under high laser energy input. However, using relatively lower energy input, particle bonding was realized through liquid phase sintering with complete melting of Ni–Cu acting as binder and nonmelting of W acting as structure. Due to the Ni–Cu solid solution phase that appeared in a wide range from 1,084 to 1,455 °C, a coherent matrix interface can be observed after solidification. The microhardness of laser-fabricated specimens varied with different powder layer thicknesses, resulting from the laser-treated condition and ability of trapped air in the loose powder bed to escape. The metallurgical mechanisms were also addressed.     

Elimination of Fuel Pressure Fluctuation and Multi-injection Fuel Mass Deviation of High Pressure Common-rail Fuel Injection System

The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system(HPCRS)including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.     

粉末冶金Ti-22Al-25Nb合金的真空热压烧结工艺

以气雾化法获得的Ti-22Al-25Nb（at.%）预合金粉末为初始原料,采用真空热压烧结工艺方法制备组织致密、成分均匀的粉末冶金Ti-22Al-25Nb合金。应用有限元软件MSC.Marc对Ti-22Al-25Nb（at.%）预合金粉末的致密化过程进行数值模拟,分析了温度和压力对Ti-22Al-25Nb粉末致密化过程的影响,揭示了粉末相对密度随温度和压力变化的规律,得到优化的烧结工艺参数,以指导热压实验烧结。通过热压烧结实验制备了组织致密、成分均匀的Ti-22Al-25Nb合金,发现1 050 ℃/35 MPa/1 h条件下烧结的合金具有最优的室温和650 ℃高温综合力学性能。     

转速对三元硼化物基金属陶瓷覆层耐磨性的影响

以Mo粉、FeB合金粉和Fe粉为基本原料,同时加入Cr、Ni、C合金元素成分,采用原位反应真空液相烧结工艺,在Q235钢基体上制备三元硼化物基金属陶瓷覆层材料。利用摩擦磨损试验测试了不同转速下三元硼化物基金属陶瓷覆层材料的耐磨损性能,研究了转速对该覆层材料耐磨性的影响。