结晶器铜板热喷涂技术的研究进展

高作业率、高浇注速度的连铸技术要求结晶器具有高强度、高耐磨性和耐腐蚀性,热喷涂技术可达到改善其表面性能的目的.通过阐述超音速火焰喷涂涂层材料在铜基体上的应用现状及对比分析各种封孔剂降低涂层孔隙率的效果后发现,采用超音速火焰喷涂金属陶瓷涂层,并且选用合适的封孔剂进行封孔处理,可以有效地提高结晶器的耐磨性和耐腐蚀性,并显著提高结晶器的寿命.     

AM50镁合金强流脉冲电子束表面改性的研究

采用强流脉冲电子束（HCPEB）对含稀土的AM50镁合金进行表面改性处理。利用金相显微镜、扫描电镜和显微硬度计等对试样的截面和表面进行观察,研究了强流脉冲电子束表面改性对其摩擦磨损性能及耐腐蚀性能的影响。结果表明：处理层的截面组织经脉冲电子柬轰击后发生了很大的变化;从表面形貌可以看出存在许多弥散分布的微米尺度的熔坑;显微硬度测试结果表明,处理层的硬度比基体的硬度明显提高;耐磨性及耐腐蚀性能均较基体提高,同时在不同处理参数下耐磨性及耐腐蚀性能有所不同。     

旋耕刀表面强流脉冲电子束改性后的耐磨性研究

为了提高农机零部件的主要磨损部件旋耕刀的耐磨性,延长其使用寿命,采用强流脉冲电子束表面改性技术处理旋耕刀常用材料60Si2Mn钢表面.采用金相显微镜分析形貌,通过显微硬度对比和摩擦磨损分析处理表面的性能,优选加速电压,将其作为优化参数作用于旋耕刀表面,并在土槽台架模拟工况试验.结果表明:电子束表面改性技术可以有效提高旋耕刀的耐磨性,对侧刃内侧处理要优于对侧刃外侧的处理;加速电压为30 kV和27 kV时,旋耕刀表面耐磨性较优,前者的磨损量较小.     

连铸结晶器铜板及表面处理技术进展

结晶器是钢坯连续铸造的关键设备,其设计和制造的优劣直接影响到连铸生产的正常与稳定.本文就目前连铸结晶器采用的铜板材料及铜板材料表面处理技术的发展现状进行了总结和分析.指出针对板坯结晶器窄面铜板易高温变形、磨损的情况,采用高强度、高导热率的弥散强化铜材料,进而延长结晶器的维修周期,提高生产效率.同时针对现有结晶器铜板表面...     

高能束技术在镁合金表面改性中的应用

针对如何提高镁合金强度、硬度、耐磨性、耐腐蚀性等综合性能这一热点问题,系统地介绍了激光束、电子束、离子束3种高能束表面改性技术的原理、方法以及在镁合金表面改性中的应用进展,总结了各工艺方法的优缺点,展望了高能束技术在镁合金表面改性中的发展前景。     

45钢离子氮碳氧三元共渗与QPQ处理对比研究EI北大核心CSCD

盐浴复合(QPQ)技术为公认的能同时提高金属材料耐腐蚀性和耐磨性的表面改性技术,但其推广使用受到环保制约。为开发绿色高效表面改性技术,探索了离子氮碳氧三元共渗(PNCO)技术,并与QPQ技术改性效果进行了对比研究。选择45钢为原材料,分别采用PNCO技术和QPQ技术进行表面改性。利用光学显微镜及扫描电子显微镜、XRD、显微硬度计、摩擦磨损试验机、浸泡腐蚀实验对两种表面处理试样的截面显微组织、物相、表面及截面硬度、耐磨性和耐腐蚀性进行测试和分析。结果表明,在510℃×4 h工艺条件下,PNCO处理获得的化合物层厚度为20.14μm,有效硬化层厚度为59μm,截面最高硬度为760HV_(0.05),磨损率为1.39×10^(-3)g·N^(-1)·m^(-1),腐蚀失重率为0.39%。XRD结果分析表明,PNCO处理后渗层形成了Fe_(x)N化合物和以Fe_(3)O_(4)为主的氧化物相。PNCO和QPQ对比研究发现,两者表层硬度、耐磨性及耐腐蚀性均相近。本研究为绿色高效表面改性技术提供了可行的研究方向。     

工业纯铁等离子体注入与氮化工艺及其性能研究

采用低电压高频率脉冲等离子体浸没离子注入与氮化技术在工业纯铁上进行氮离子注入及氮化强化处理,研究了不同脉冲宽度下,工业纯铁等离子体浸没离子注入与氮化处理的结构及性能.通过X射线衍射谱(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、显微硬度、销-盘磨损实验,研究了工业纯铁氮离子注入及氮化后的结构、断面组织、表面元素含量、显微硬度、摩擦磨损性能;通过电化学极化方法在0.9%NaCl溶液研究了改性层的耐腐蚀性.研究结果表明:氮等离子注入及氮化后能显著提高纯铁表面的显微硬度、耐磨性和耐腐蚀性能,且表面形成结构为Fe3N和Fe4N的针状组织,针状组织是提高纯铁性能的关键因素;高脉冲宽度下进行等离子注入及氮化有利于提高纯铁表面的机械性能和耐腐蚀性能.     

结晶器电镀工艺的改进

结晶器是决定连铸生产效率和连铸坯表面质量的关键因设备之一.板坯连铸结晶器是由4块铜板组合而成的,因此铜板的使用寿命也就直接影响连铸坯的表面质量和连铸的生产效率,而铜板的使用寿命又取决于铜板表面镀层的耐磨性与耐用性.Ni/Ni\|Fe复合镀层,由于产品质量不稳定,影响了连续生产效率.为此我们采用一次电镀技术,不但使产品质量得到提高,而且铜板的使用寿命延长.此技术对我国连铸技术的发展将起到积极地推动作用,且具有实际的应用价值.     

磁性法和电涡流法测厚仪的特点

概述 表面工程技术有着广泛的应用领域,表面性能的监控和测量发展极为重要.体现表面性能的指标有很多,如硬度、厚度、结合强度、附着强度、耐磨性、耐腐蚀性、抗破裂性等,其中涂层和镀层的厚度是一项重要的参数.通过测量涂层和镀层的厚度也可以间接反映表面的耐磨性、耐腐蚀性等.因此,涂层和镀层的厚度测量常常作为评判表面性能的初检而得以广泛使用.     

石墨烯添加量对Ni基-石墨烯复合镀层性能的影响

为提高连铸结晶器的表面性能,以NiSO_4·6H_2O为主盐,用电镀的方法在炼钢连铸结晶器铜板上制备了Ni基-石墨烯复合镀层。利用场发射扫描电镜(FE-SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机等分析手段,研究了镀液中石墨烯浓度对复合镀层组织、成分、形貌、厚度、相结构、硬度及耐磨性的影响,分析了复合强化机理。结果表明:Ni基-石墨烯复合镀层中C含量随着石墨烯添加量的增加而增加,石墨烯在镀层表面及截面上的分布较均匀;镀层的平均摩擦系数随石墨烯添加量的增加而减小,显微硬度显著提高;当镀液中石墨烯浓度为120 mg/L时,镀层的平均显微硬度为1 142 HV_(1N),摩擦系数为0.548,耐磨性优于目前生产上的常规Ni-Co合金镀层,可以有效地保证铸坯质量和提高结晶器使用寿命。     

Near net shape processing of metal and ceramic composite ingot mould

Abstract

A new pressureless infiltration method was developed to place a silicon dioxide particle reinforced layer on the surface of an industrial ingot mould without changing the production process of the ingot mould. The morphology and structure of the composite layer were investigated by optical and scanning electron microscopy. The service life and thermal characteristics of the reinforced mould were tested during their use in practical casting processes. It was found that a 4 mm thickness composite layer can be obtained on the surface of an ingot mould with this method. The reinforced mould can be used directly without any extra machining process. The service life of the new mould is twice that of the original for the same application conditions. The heat resistance and wear resistance of the mould were evidently improved.     

AZ91D镁合金的触变成形及其磨损性能的研究

研究了加热时间和模具预热温度对AZ91D镁合金触变成形性、组织和磨损性能的影响。结果表明,适合AZ91D镁合金触变成形的最佳加热时间为90min(在585℃),模具预热温度为350℃;在此工艺条件下,初生相颗粒较圆整、粒度较小,组织最致密,相应地,其耐磨性也最好;与金属型铸造相比,明显地提高了耐磨性。     

连铸结晶器表面强化层的研究现状和发展趋势

钢铁连铸结晶器作为连铸机的核心部件，其工作的可靠性、稳定性和耐用性便成为人们十分关心的问题。人们采用电镀、热喷涂等表面强化处理技术在结晶器表面制备一层保护层，以延长结晶器的使用寿命。阐述了结晶器表面强化技术的研究现状，并展望了结晶器的表面强化技术。     

不锈钢低温盐浴表面氮化技术发展与现状

不锈钢具有良好的耐蚀性、韧性和可加工性,但其硬度低、耐磨性差,严重制约了其在有磨损腐蚀要求环境体系中的应用.为了提高不锈钢的抗磨损性能,通过低温活性盐浴表面处理技术提高其耐磨性的同时不降低其耐蚀性,使得其在具有磨损的腐蚀介质环境中能够提高其抗磨损性能而不被腐蚀,可延长其使用寿命.本文系统地介绍了低温活性盐浴表面氮化处理技术的发展、原理及应用和处理后表面氮化层的特点、组织和表面性能.低温活性盐浴表面处理后,表层活性N原子扩散在奥氏体间隙中形成过饱和固溶体的S-相,产生特殊的位错-应力FCC结构,使得奥氏体晶格发生严重变形,不但提高了其腐蚀性,同时大大提高了其硬度,使得不锈钢硬度能够达到1 000 HV0.1,其抗磨损性能亦得到了显著提高.     

生物材料的离子束表面改性

随着表面处理技术的发展,国内我对如何改善现有的生物材料表面的各种性能,如耐蚀性,耐磨性,生物相容性等进行了研究。各种表面处理的方法受到高度重视,其中离子束表面改性技术,由于其对材料本体无负效应,已被证明是最为成功的一种。本文在综述离子束改性技术在生物材料及器械方面应用的同时,提出将梯度功能材料的新概念与离子束改性技术相结合,用以制备表面性能优异的仿生生物材料。     

离焦量对激光熔覆层组织及性能的影响

目的改善40 Cr钢表面性能,提高其表面硬度、耐磨性及耐蚀性。方法利用扫描电子显微镜、显微硬度计、磨损试验机、电化学测试系统等对激光熔覆层组织及性能进行观察和分析。结果离焦量越大,熔覆粉末及基体表面熔化深度越浅,通过控制适当的离焦量可以获得结合良好的涂层;离焦量为110 mm时,激光束的快热快冷作用能获得细小均匀的组织,细晶能保证较高的硬度,耐磨性及耐蚀性均较好。结论 40Cr钢经激光熔覆处理后可显著改善其表面性能,适宜的离焦量有利于获得最佳性能。     

等离子钴基熔覆层的组织和性能研究

等离子熔覆技术是采用等离子束为热源,在金属表面获得优异的耐磨、耐蚀、耐冲击等性能的新型材料表面改性技术。本工作对低碳马氏体钢表面进行等离子熔覆处理,研究钴基合金熔覆层的显微硬度、金相组织。研究结果表明:钴基合金熔覆层的硬度达942HV。熔覆层组织主要由树枝晶和孢状晶粒组成,熔覆层与基体界面结合良好,无裂纹。     

Coatings and hardfacing alloys for corrosion and wear resistance in diesel engines

Abstract

The potential for surface engineering solutions to increase the corrosion and wear resistance of diesel valves is examined with regard to operation in residual fuel oil combustion products. The environment in which the exhaust valve operates is discussed. The corrosion test is used to sort the 27 coating treatments and 16 hardfacing alloys examined. H ardfacing materials showing the greatest potential are also evaluated in hot wear tests. As reference materials, En 52 steel, Nimonic 80A, and Stellite 6 are included. Corrosion tests over the temperature range 500–700°C have shown that the surface treatments can be ranked in terms of their composition and expected metal surface temperature. Good corrosion resistance to residual fuel oil combustion products reflects primarily the content of the alloy, the base metal (Fe, Ni, or Co) being of secondary importance. Refractory metals (Ti, Nb, Ta, Mo, and W) and other minor alloying additions do not significantly alter the corrosion behaviour, unless they are present in large quantities. Hot wear tests (650°C, 80 MN m^?2 contact pressure) of candidate hardfacing alloys have also demonstrated the importance of the Cr content of the alloy. This probably results from the ease of formation of a protective glaze, lowering the coefficient of friction and therefore the wear rate. Additions of refractory metals were beneficial. Since optimum wear resistant alloys contained high levels of Mo and vv: they were poor in terms of corrosion resistance. It is therefore necessary to balance wear resistance against corrosion resistance in the selection of materials for residual fuel oil service. Two coating systems, vacuum plasma sprayed Ni–50Cr and a chromised diffusion treatment appeared to have potential as valve surface treatments for improved corrosion resistance; and two hardfacing alloys, Tristelle TS2 and Colmonoy 8, offered balanced behaviour as seat materials with acceptable wear resistance and improved corrosion performance. These materials have been evaluated in the engine tests of three different diesel engine manufacturers.

MST/3157     

The corrosion and wear resistances of magnesium alloy (LZ91) electroplated with copper and followed by 1 μm-thick chromium deposits

The Mg-Li-Zn alloy, LZ91, is a potential material for industrial application owing to its high specific strength. However, the LZ91 has so high chemical reactivity that it is easily corroded in air and an aqueous environment. In this study, an eco-friendly electrodeposition method was proposed to obtain a protective Cr/Cu coating on the LZ91 substrate. That is, the LZ91 surface electroplated a Cu undercoat in an alkaline Cu-plating bath and followed by decorative 1 μm-thick Cr electroplating in a plating bath with trivalent chromium ions. After electroplating, some of the Cr/Cu-deposited specimens were heated with a reduction flame for 0.5 s to increase the hardness of Cr-deposit. The wear resistance of as-plated and flame-hardened Cr/Cu-coated LZ91 specimens was estimated with ball-on-plate wear tester by using a steel-ball counterpart. Whereas, their corrosion resistance was evaluated in a 0.1 M H₂SO₄ solution before and after wear test. Experimental results show that a Cu deposit could be uniformly electroplated on the LZ91 surface by using our proposed electroplating method. The corrosion resistance of LZ91 was markedly improved after decorative 1 μm-thick Cr electroplating. After wear test, the steel counterpart was ground obviously with either as-plated or flame-hardened Cr/Cu-coated LZ91 specimen. According to the results of electrochemical corrosion test, some parts of the Cr deposit were peeled off from worn flame-hardened Cr/Cu LZ91 surface. This reduces its corrosion resistance significantly. On the other hand, the corrosion resistance of as-plated Cr/Cu LZ91 was not changed after wear test. That is, an as-plated Cr/Cu-coated LZ91 specimen could have good corrosion and wear resistance.