等离子体电解氧化陶瓷膜的工艺研究

利用等离子体电解氧化技术在铝合金6063表面生成了氧化物陶瓷膜．测试了氧化膜表面厚度和硬度，观察了膜层表面形貌，分析了氧化陶瓷膜的成分，探讨了不同电流密度对形成陶瓷膜厚度和硬度的影响．结果表明：铝合金6063表面陶瓷膜的厚度和硬度随电流密度的增大而提高，但有一极限值平均电流密度极限值为25A／dm^2；随氧化时间的延长而增厚增硬，但也有一极限值，氧化时间极限值为45min．     

氧化钛含量对氧化铝基涂层磨损性能和机制的影响

研究了TiO2含量对大气等离子喷涂Al2O3基涂层的晶体结构组成相、显微硬度、摩擦磨损性能和磨损机制的影响.选用重量百分比为0,13%,40%这3种TiO2含量参量,即纯A12O3,AI2O3-13%(wt)TiO2和AI2O3-40%(wt)TiO2陶瓷涂层.采用XRD分析涂层的晶体结构组成相,Vickers显微硬度计评价显微硬度.采用SRV摩擦磨损试验机,通过AISI52100钢球和A12O3陶瓷球2种材料本质差异甚大的对摩副,在干摩擦条件下评价涂层的摩擦磨损性能,并通过扫描电镜观察涂层磨损机制.结果表明,Al2O3基涂层的显微硬度随TiO2含量增加而降低;A12O3基涂层皆显示出抗磨性能随TiO2含量增加而降低,而与对摩副材质无关.涂层中含有TiO2无益于提高Al2O3基涂层的摩擦磨损性能.     

Microstructure and Wear Behaviour of Laser-Induced Thermite Reaction Al2O3 Ceramic Coatings on Pure Aluminum and AA7075 Aluminum Alloy

Wear-resistant laser-induced thermite reaction Al_2O_3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding(one-step method)and laser cladding followed by laser re-melting(two-step method)using mixed powders CuO-Al-SiO_2 in order to improve the wear properties of aluminum and aluminum alloy,respectively.The microstructure of the coatings was characterized by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature.Owing to the presence of hardα-Al_2O_3 andγ-Al_2O_3 phases,the coatings exhibited excellent wear resistance.In addition,the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.     

Comments on process of duplex coatings on aluminum alloys

Despite the great achievements made in improvement of wear resistance properties of aluminum alloys,their applications in heavy surface load-bearing are limited. Single coating is insufficient to produce the desired combination of surface properties. These problems can be solved through the duplex coatings. The aim of the present study is to overview the research advances on processes of duplex coatings on aluminum alloys combined with micro plasma oxidation process and with other modern processes such as physical vapour deposition and plasma assisted chemical vapour deposition and also to evaluate the performance of micro plasma oxidation coatings in improving the load-bearing, friction and wear resistance properties of aluminum alloys in comparison with other coatings. Wherein, a more detailed presentation of the processes and their performances and disadvantages are given as well.     

Plasma preparation method and tribological properties of diamond-like carbon coating on magnesium alloy AZ31 substrate

Magnesium alloys are light weight and exhibit good recyclability but suffer from low hardness and wear resistance.In this study,the hardness and wear resistance of AZ31 magnesium alloy were improved by depositing diamond-like carbon(DLC)films as hard protective coatings using ion-beam-enhanced deposition with various CH_4/H_2 ratio,gas flow rates and accelerating voltages.The supporting effect of the magnesium alloy was enhanced by the production of a graded interfacial layer which is composed of film atoms and substrate atoms.The composition and mechanical properties of the DLC coatings were characterized using scanning electron microscopy(SEM),Raman spectroscopy,Rockwell test and nano-indentor.The tribological properties of the coating were also investigated using a frictional surface microscope with an in situ observation system and friction force measurements.The DLC films were characterized by a lower intensity ratio of the D-peak to G-peak(I_D/I_G),higher hardness,and improved tribological properties when deposited at a lower accelerating voltage(6 kV).At the CH_4/H_2 ratio of 1:99 and 6 sccm/6 kV,minimum I_D/I_G values of 0.62,relatively low friction force value of 0.12 N,and a maximum hardness of 4056HV were attained respectively.In addition,the DLC film exhibited improved wear resistance and a shallower wear track at this condition.     

铝合金旋转喷吹净化工艺的研究

从表征流态的物理量出发，通过计算建立了铝合金旋转喷吹除气系统的物理模型，以CO2-NaOH体系来模拟实际的铝液净化，用CO2通入溶液后引起的pH的变化来模拟铝液中含氢量的变化．研究了影响铝合金旋转喷吹净化的因素，结果表明转子转速对净化效果影响最大，气流量次之．通过模拟实验获得最佳工艺参数及工艺参数的选取原则，并通过传统的C2Cl6的净化工艺和旋转喷吹净化工艺的比较中证实了旋转喷吹净化工艺优异的除氢效果．     

Microstructure and corrosion properties of laser cladding MoNi based alloy coatings

Mo-based alloys are widely used for their excellent wear and corrosion resistance as well as high temperature resistance.Mo-NiCrBSi and Mo-Ni alloy coatings were prepared on 1020 water wall tube by laser cladding technology in the present study.The microstructure and phase compositions were analyzed by means of the scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS)and X-ray diffractometry(XRD).The corrosion properties of the coatings were evaluated by an electrochemical experiment at room temperature in 3.5 wt.%NaCl electrolyte.With increasing content of Mo,the structure homogeneity in Mo-Ni coatings deteriorated,the grain size increased,the average hardness and the corrosion resistance declined,due to the more content of harmful phases.Compared to the Mo-Ni coatings,the overall performance was better for the Mo-NiCrBSi,which had the higher hardness contributed by the element B and Si as well as the better corrosion resistance due to the addition of Cr.     

Effects of ZrO_2 Nanoparticles on the Microstructure and Thermal-protective Properties of PEO Coating on Al-12.5%Si Alloy

PEO ceramic coatings including ZrO_2-Al_2O_3-SiO_2 in three phases were prepared on an Al-12.5%Si alloy in electrolyte solutions containing ZrO_2 nanoparticles. The microstructures and phases of the coatings were analyzed by SEM and XRD, and the heat insulation performance and the thermal shock resistance of the coatings were investigated. The compactness of the coating increased significantly and the hindrance of the Si element on plasma electrolytic oxidation process was effectively weakened. The growth rate of the coating was improved substantially with the addition of ZrO_2 nanoparticles. The PEO ceramic coatings are primarily composed of SiO_2 and high temperature steady phases such as a-Al_2O_3 and c-ZrO_2. Both the content of c-ZrO_2 and the heat-insulating property of the coating increased significantly. The ceramic coatings with special microstructure and composition formed in the solutions containing ZrO_2 nanoparticles possess excellent heat insulation performance and thermal shock resistance.     

陶瓷/金属复合耐磨涂层的性能评价

应用大气等离子喷涂（APS）技术制备陶瓷／金属复合耐磨涂层试样，并对其硬度，结合强度，微观结构和耐磨性等性能进行评估，结果表明Al2O3-TiO复合涂层在耐磨性方面好于WC－NiCrAl复合涂层，而WC－NiCrAl复合涂层在结合强度性能上好于Al2O3-TiO2复合涂层。     

碳钢Cr-Ti共渗及Al-Ti共渗层的组织和性能

为了提高碳钢构件的硬度、耐磨性和耐蚀性，对35钢及20钢实施Cr—Ti共渗及Al-Ti共渗，用X射线、EPMA、显微硬度及摩擦磨损实验等分析测试方法，研究了渗层的组织和性能．结果表明，35钢Cr—Ti共渗层外侧富Cr、内侧富Ti，在3．5％NaCl和10％H2SO4溶液中有良好的耐蚀性；渗层表面硬度HV0.2=1900，耐磨性比17Cr2Ni2Mo渗碳钢对比试样提高3倍．35钢Al—Ti共渗层外侧富Ti、内侧富Al，在10%H2SO4溶液中的耐蚀性较差；渗层表面硬度为HV0.2=400，但耐磨性仍比对比试样提高近一倍。     

脉冲N离子束轰击对TiAlN膜层显微硬度影响的研究

采用俄罗斯UVN 0.5D2I脉冲离子束辅助电弧离子镀沉积设备,在高速钢W18Cr4V基材上沉积TiAlN膜层。研究了膜层沉积之前N离子束轰击基材以及膜层沉积过程中N离子束辅助轰击对TiAlN膜层显微硬度的影响。结果表明:膜层沉积之前,N离子轰击得到高度洁净的表面,使基材的显微硬度由原来的900HV0.01提高到1230HV0.01。膜层沉积过程中,脉冲N离子束轰击,消除了膜层中的硬度"软点"及阴影效应,增加(Ti,Al)N相的含量,膜层的内部产生了压应力,这些因素显著提高了膜层的硬度,膜层的最高硬度为2530HV0.01。但轰击能量不能过高,否则会降低膜层的显微硬度。     

Structure and properties of Ti-Si-N coatings synthesized by combining cathode arc and middle-frequency magnetron sputtering

Ti-Si-N composite coatings were synthesized on a novel combining cathode and middle-frequency magnetron sputtering system, designed on an industrial scale. Ti was produced from the arc target and Si from magnetron target during deposition. The influences of negative bias voltage and Si content on the hardness and microstructure of the coatings were investigated. The composite coatings prepared under optimized conditions were characterized to be nc-TiN/a-Si₃N₄ structure with grain sizes of TiN ranging from 8–15 nm and exhibited a high hardness of 40 GPa. The enhancement of the hardness is suggested to be caused by the nanograin-amorphous structure effects.     

Thermal shock resistances of FeMnCr/Cr<Subscript>3</Subscript>C<Subscript>2</Subscript> coatings deposited by arc spraying

Arc spraying with the cored wires was applied to deposit FeMnCr/Cr₃C₂ coatings on low carbon steel substrates, namely FM1, FM2 and FM3. Thermal shock resistances of the coatings were investigated to assess the influence of Cr₃C₂ content on thermal shock resistance. Characteristics of the coatings under thermal cycling test were studied by optical microscopy, field emission scanning electron microscope (FE-SEM) and energy dispersion spectrum (EDS), X-ray diffraction (XRD). The experimental results show that hardness of the coatings increases, bonding strength decreases slightly with increase of the Cr₃C₂ content of the coatings. As a result, FM2 coating possesses the best thermal shock resistance, attributing to its better thermal expansion matches and wettability than those of FM3 coating, less oxide rate than that of FM1 coating restraining from cracks formation and propagation in coatings.     

Microstructure and wear behaviour of laser-induced thermite reaction Al<Subscript>2</Subscript>O<Subscript>3</Subscript> ceramic coatings on pure aluminum and AA7075 aluminum alloy

Wear-resistant laser-induced thermite reaction Al2O3 ceramic coatings can be fabricated on pure Al and AA7075 aluminum alloy by laser cladding （one-step method） and laser cladding followed by laser re-melting （two-step method） using mixed powders CuO-Al-SiO2 in order to improve the wear properties of aluminum and aluminum alloy, respectively. The microstructure of the coatings was characterized by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The wear resistance of the coatings was evaluated under dry sliding wear test condition at room temperature. Owing to the presence of hard α-Al2O3 and γ-Al2O3 phases, the coatings exhibited excellent wear resistance. In addition, the wear resistance of the coatings fabricated by two-step method is superior to that of the coatings fabricated by one-step method.     

综合利用包钢高炉布袋除尘灰制备微晶玻璃的试验研究

以包钢高炉布袋除尘灰、二氧化硅、氧化钙、氧化铝为主要原料,采用熔融法制备CaO-Al2O3-SiO2系微晶玻璃.利用DSC,SEM等方法对该玻璃体系进行测试,探讨了微晶玻璃中布袋除尘灰含量对晶化行为的影响.试验结果表明,布袋除尘灰含量的利用率可达到50%.本研究为包钢高炉布袋除尘灰综合利用提供了途径,并有效地解决了环境污染和占地问题.     

高强度耐磨铸造铝合金的研究

经优化设计合金成分及组织，应用普通冶炼方法与设备，研制出三种新型高强度铸造铝合金的过程．合金熔炼之后经Ｔ６处理，其强度、硬度、塑性和耐磨性，都远超过传统铸造铝合金ＺＬ１０８且生产工艺简单，成本低廉，具有广阔的应用前景．     

钛合金微弧氧化抗高温氧化研究现状

钛合金因具备高强度、耐蚀性及比强度高等特点被广泛应用于军用及民用等各个领域。但是,其在高温环境使用时会发生高温氧化反应,导致其性能降低,限制了它的使用。微弧氧化（MAO）技术可使钛合金表面原位生长一层致密的氧化膜,膜层与金属基体结合能力强,拥有一定的耐磨、耐蚀及抗高温等特性,且其工艺流程简单高效、成本低而环保,可明显提高钛合金的抗氧化性,延长其在高温条件下的服役时间。综述了MAO技术在钛合金抗高温氧化领域的研究现状,总结了反应参数、电解液、微弧氧化反应时间及电源模式等条件对微弧氧化陶瓷膜层结构和抗高温氧化性能的影响。     

熔盐法制备Al_2O_3粒子增强铝基复合材料的工艺研究

用碱性熔盐作为载体将Al_2O_3粒子较均匀地添加到铝合金熔体中是获得Al_2O_3粒子增强铝基复合材料的新方法。本文对比了熔盐种类、配比、加入方法及Al_2O_3粒子大小对其在铝基体中分布均匀性的影响,测定了Al_2O_3粒子强化铝基铸选复合材料的机械性能。     

Al-Si合金的等离子电解氧化及膜层组织性能研究

为提高铝合金材料在高温下的使用性能,采用等离子电解法在锆盐体系和锆盐-钇盐复合体系中于铝硅合金表面制备了陶瓷层.分析了电解液浓度及成分对起弧电压、膜层厚度、组织及隔热温度的影响.研究结果表明:两种电解液体系中随电解液浓度的增大,起弧电压降低,陶瓷层厚度和隔热温度先增大后减小.与锆盐体系相比,锆盐-钇盐体系中起弧电压显著降低,膜层厚度与隔热温度提高.锆盐体系陶瓷层中生成了常温下稳定的t-ZrO2,锆盐-钇盐体系涂层中则生成了立方相的c-Y0.15Zr0.85O1.93.制备的两种陶瓷膜层与传统的硅酸盐膜层相比,其表面孔洞较少,锆盐-钇盐体系相对于锆盐体系其陶瓷层更加均匀、致密.     

爆炸喷涂Al2O3陶瓷涂层的摩擦磨损性能

爆炸喷涂是提高材料表面性能的表面喷涂技术之一.本文旨在通过表面喷涂提高45钢基体表面的耐磨性、耐冲击性等性能.采用爆炸喷涂方法在45钢基体材料上喷涂Al2O3陶瓷和团聚陶瓷涂层,在摩擦磨损试验机上进行Al2O3陶瓷涂层的磨损试验,X衍射仪测试涂层表面结构,JB/T7509—94铁试剂方法测试涂层的孔隙率.通过分析和比较45钢基材与爆炸喷涂Al2O3陶瓷涂层的摩擦磨损性能,实验结果表明,喷涂Al2O3陶瓷涂层可以改善基材45钢的耐磨损性能,延长其使用寿命.此外,研究发现,团聚Al2O3陶瓷涂层比Al2O3陶瓷涂层要更耐磨;而爆炸喷涂Al2O3涂层的质量要好于等离子喷涂和火焰喷涂Al2O3陶瓷涂层.