化学沉积法制备Ni-P-SiC复合镀层的研究

研究了在碳钢基材表面进行化学沉积Ni-P-SiC复合镀层的工艺和条件,对镀层的成分进行了扫描分析,对镀层的金相组织进行了观察分析;结果表明SiC硬质纳米粒子嵌入,使Ni-P合金基质产生沉淀强化,使镀层硬度增加.通过对磨实验和腐蚀实验证明,复合镀层可使碳钢零件耐磨性能提高3倍,可使碳钢零件耐蚀性能提高4倍,有效地延长了钢铁零件的使用寿命.     

热处理温度对CrMoNi铸铁基化学镀Ni-P层显微结构与性能的影响

采用化学镀技术在CrMoNi高合金铸铁表面沉积Ni—P合金镀层,采用维氏硬度仪、M-2000摩擦磨损机、SEM和EDAX等手段研究了热处理温度对Ni-P合金镀层组织结构和性能的影响,并对磨损机理进行了分析．研究结果表明：CrMoNi合金基体表面沉积Ni—P合金镀层能有效改善CrMoNi合金基体硬度和耐磨性．经过350℃热处理时,获得的Ni-P合金镀层硬度达到极值1072HV,为基体硬度的4．5倍,耐磨性最佳,磨损率仅为基体的0．68％o,镀层的磨损机制为轻微的黏着磨损．     

Microstructure and performance of laser cladding TiB2 and Nickel-coated graphite composite coating on stainless steel 9Cr18

Stainlesssteel9Cr18withhighhardnessandanti wearpropertyiswidelyusedinthefieldsofbothna tionaldefenseandciviluse,especiallyapplicationintheaero enginebearingsandnationaldefenseaccoutre ments.Thetechnologyoflasercladdinghighhardness,antiwearandantifrictionc…     

PTA clad （Cr, Fe）7C3/γ-Fe in situ ceramal composite coating

A wear-resistant （Cr, Fe）7C3/γ-Fe in situ ceramal composite coating was fabricated on the substrate of 0.45wt%C carbon steel by a plasma-transferred arc cladding process using the Fe-Cr-C elemental powder blends. The microstructure, microhardness, and dry-sliding wear resistance of the coating were evaluated. The results indicate that the microstructure of the coating, which was composed of （Cr, Fe）7C3 primary phase uniformly distributed in the γ-Fe, and the （Cr, Fe）7C3 eutectic matrix was metallurgically bonded to the 0.45wt%C carbon steel substrate. From substrate to coating, the microstructure of the coating exhibited an evident epitaxial growth character. The coating, indehiscent and tack-free, had high hardness and appropriate gradient. It had excellent wear resistance under the dry sliding wear test condition.     

Preparation and High Temperature Oxidation Properties of Micro-Crystalline MGH754 ODS Alloy Coatings

A special coating technique, electro-spark deposition (ESD), was developed to produce micro-crystalline ODS MGH754 alloy coatings on a commercial ICrl8NigTi stainless steel and a cast Ni20Cr alloy substrates. The coatings have a very fine grain structure and metallurgical bonding with the substrates. The isothermal oxidation tests at 1000 ℃ in air showed that the micro-crystalline ODS alloy coatings had a much reduced oxidation rate and improved scale spallation resistance compared with the uncoated alloys. The selective oxidation of Cr was greatly promoted to form protective and continuous Cr2O3, scales on the alloy surface. Micro-crystallization and oxide dispersions have synergistic effects on the improvement of oxidation resistance. The beneficial effects were discussed based on the experimental results.     

Microstructure and wear resistance of electro-thermal explosion sprayed stellite coating used for remanufacturing

Electro-thermal explosion directional spraying was used to prepare the stellite coating on substrate of the AISI 1045 steel. The morphologies of cross-section and worn scar, porosity, distribution of elements, microhardness and wear resistance of the coating were determined by means of SEM, EDAX, micro-hardness tester and sliding wear tester. Because of the compact construction, good bonding and high hardness, the coating is characterized by good wear resistance. The results show that the mainly failure mode of the stellite coating is microplowing.     

Development of centrifugal casting high speed steel rolls

The present study aims at developing the high speed steel (HSS) as roll materials to replace the traditional roll materials such as the alloy cast iron and powder metallurgical (PM) hard alloy. The HSS roll billet was formed by centrifugal casting, and the billet was rough machined after soften annealing heat treatment, then it was quenched and tempered to get suitable hardness and toughness. After that the HSS roll was finish machined to the final dimension of φ285 mm in the outer diameter, φ160 mm in the inner diameter and 120 mm in width and its surface hardness was tested. Finally the HSS roll was used in high speed wire rod mill. The test results show that a high and homogeneous hardness can obtain on the work surface of HSS rolls, the surface hardness is 63-65HRC and its variation is smaller than 2HRC. The impact toughness of this kind of HSS is about 16 J/cm2. The results of on-line service investigation in high speed wire rod mill indicate that the HSS rolls have excellent wear resistance, the     

Cr3C2对等离子钴基堆焊层组织及性能的影响

采用等离子堆焊技术在低碳钢表面制备钴基合金堆焊层(Co40)及添加质量分数20%和40%Cr3C2的钴基合金复合堆焊层(Co40+20%Cr3C2,Co40+40%Cr3C2)。利用光学显微镜、扫描电镜、X射线衍射仪以及磨损实验机等研究不同添加量的Cr3C2对钴基合金堆焊层组织和耐磨性能的影响。结果表明:Co40堆焊层由γ-Co和Cr23C6组成;添加Cr3C2粉末后,堆焊层出现未熔的Cr3C2和Cr7C3及Cr23C6相,且明显改变了其组织特征,Co40+20%Cr3C2堆焊层仍以亚共晶方式结晶,但其组织得到明显的细化和均匀化,而Co40+40%Cr3C2堆焊层转变为过共晶方式结晶,其组织由大量初生碳化物和枝晶组织组成;Co40+Cr3C2复合堆焊层的硬度和耐磨性较Co40堆焊层均得到显著提高,且随着Cr3C2添加量的增加而相应提高。     

Influence of Re-Ti modification on the high impact wear resistance of high Si bainitic cast steel

The effect ofrare earth(Re)and titanium(Ti)multi-modification on the impact wear behavior of Mn-B high-Si bainitic cast steel was investigated systematically.The experiments show that the impact wear resistance can be improved greatly with the addition of Re and Ti.Its wear loss is only about 1/3-1/2 as large as that of the unmodified bainitic cast steel.By the Re/Ti modification,coarse dendrite grains and bainitic/martensite duplex structure have been refined effectively,and the impact toughness ofthe bainitic cast steel is nearly tripled(10mm×10 mm×55 mm with unnotched sample).Consequently,the modified bauutic cast steel possesses good wear resistance under high impact.For both modified and unmodified bainitic cast steels,high hardness white layer and deformed zone are developed beneath the worn surface under the lugh impact wear,but the formation and propagation of cracks are different for these bainitic casting steels.Different models for the formation and propagation of cracks for both modified and unmodified bairutic cast steels under high impact wear are proposed.     

2738模具钢表面激光熔覆Ni基WC复合涂层的摩擦磨损性能

在2738模具钢表面通过CO2激光熔覆制备Ni基WC复合涂层。分别对2738钢基体和Ni-WC激光熔覆层进行干摩擦试验。用三维表面形貌仪测量磨损体积,用扫描电镜观察磨痕的表面形貌。试验结果表明,Ni-WC复合涂层试样的硬度显著提高,表面硬度超过1200HV,保证了Ni-WC熔覆层的耐磨性。熔覆层的平均摩擦因数约为0.24,与2738钢基体的摩擦因数0.43相比,降低了约44%。熔覆试样的比磨损率比基体试样的比磨损率下降了96.7%,WC硬质相提高了摩擦副表面的承载能力。磨粒磨损为Ni-WC复合涂层的主要磨损机理。     

线材火焰喷涂层的组织和性能研究

本文研究了用T8钢丝对QT90-2铸铁基材进行火焰喷涂后的涂层组织和性能。结果表明,涂层是由喷涂材料、氧化物、气孔组成的混合组织。用电火花镍拉毛的过渡层是铁镍合金层,局部区域有少量马氏体组织。涂层与基材的粘结强度为9.50MPa;涂层自身结合强度为150MPa。涂层的耐磨性高于基材,用该法修复被磨损的汽车发动机曲轴轴颈是可行的。经济效益显著。     

Microstructure and wear resistance of electro-thermal explosion sprayed stellite coating used for remanufacturing

Electro-thermal explosion directional spraying was used to prepare the stellite coating on substrate of the AISI 1045 steel. The morphologies of cross-section and worn scar, porosity, distribution of elements, micro-hardness and wear resistance of the coating were determined by means of SEM, EDAX, micro-hardness tester and sliding wear tester. Because of the compact construction, good bonding and high hardness, the coating is characterized by good wear resistance. The results show that the mainly failure mode of the stellite coating is micro-plowing. Foundation item: Project(2003AA331130) supported by Hi-tech Research and Development Program of China; Project(50235030) supported by the National Natural Science Foundation of China     

镁合金表面热喷涂Al-Al2O3/TiO2梯度涂层研究

采用氧乙炔火焰喷涂法，在AZ91D镁合金表面制备Al-Al2O3/TiO2梯度涂层。利用扫描电镜和电子探针对涂层的组织形貌、成分进行了分析。采用热震法测试了涂层结合强度，并对涂层耐磨性进行了测试。实验结果表明：Al梯度层与基体及陶瓷涂层结合良好。涂层具有较高的硬度、耐磨性及抗热震性。     

等离子喷涂NiCr/Cr_2C_3、Ni/C及其复合涂层的耐磨性能

为了加强车辆机械零件的表面防护,采用等离子喷涂工艺在304N不锈钢表面分别制备了NiCr/Cr_2C_3涂层、Ni/C涂层以及NiCr/Cr_2C_3和Ni/C复合涂层,观察了涂层组织形貌,测试了涂层硬度和耐磨性,分析了涂层的摩擦磨损机理.结果表明,3种涂层中NiCr/Cr_2C_3和Ni/C复合涂层的耐磨性能最好.金属粘结相NiCr可以起到足够的支撑作用,从而防止涂层剥离与黏着磨损的产生.Ni/C作为固体润滑剂,通过自润滑作用降低了涂层的整体摩擦系数.     

高能脉冲类激光熔覆镍基合金层的组织及性能

为了提高304不锈钢表面的综合性能,采用高能脉冲类激光熔覆沉积技术在304不锈钢表面制备了镍基合金熔覆层.采用扫描电子显微镜、能谱仪、X射线衍射仪、销-盘磨损试验机与电化学测试系统对镍基合金熔覆层的显微组织、相结构、耐磨损性能和电化学腐蚀性能进行了研究.结果表明,镍基合金熔覆层与304不锈钢基材呈良好的冶金结合,熔覆层的相对耐磨损性为304不锈钢基材的4.4倍.熔覆层组织由γ-Ni基体相、Ni_3Mo、Fe_7Mo_3和Cr_(23)C_6碟状增强相与不规则棒状增强相组成.增强相是提高耐磨损性能的主要原因,增强相与基体相的电极电位差是导致腐蚀电流密度增加的主要原因.     

Mierostrueture and Properties of Coating from Cemented Carbide on Surface of H13 Steel

The microstructures and properties of coating from cemented carbide on the substrate of H 13 by vacuum powder sintering were studied. The effect of sintering temperature on the microstructures of coating was discussed. The interface characteristics between coating and H 13 steel substrate, microhardness distribution and wear resistance in the coating were analyzed. The coating from cemented carbide with thickness of 1-3 mm by vacuum powder sintering at temperature ranging from 1280℃to 1300 ℃ was obtained. The experimental results indicated that the coating with microhardness of HV 1600 favorable to wear resistance is strongly bonded with the H 13 steel substrate by mutual diffusion and penetration of Fe,Cr, Mo,V in substrate towards the coating and W, Co,Ni in coating towards the substrate.     

冷作模具钢激光熔覆Ni基合金组织和性能研究

为提高Cr12MoV模具钢硬度和耐磨性,研究采用激光熔覆技术在其表面制备Ni基合金。研究结果表明,涂层显微组织为异向生长的树枝晶,涂层相结构为γ-(Fe,Ni)、Cr7C3、BNi2以及Ni-Cr-Fe相。由于细晶强化、固溶强化和第二相强化作用,使熔覆层平均硬度比基体硬度提高了175%。涂层摩擦系数为0.2,明显小于基体（0.5）,涂层的磨损体积较基体提高1个数量级。     

热处理对铜基化学镀镍层结构和性能的影响

采用化学镀技术在紫铜表面制备化学镀镍层,结合OLYMPUS、XRD、HVS-1000等方法研究不同热处理温度对镀层结构和性能的影响,分析不同热处理温度与镀层表面形貌、微观结构、显微硬度和耐磨性的关系。结果表明,经500℃热处理后,镀层出现明显晶界,形成了大量与Ni相共格的高硬质相Ni3P,镀层硬度和耐磨性均达到最佳,此时镀层显微硬度为1 284 HV,磨损量为2.6 mg。     

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.     

The effect and mechanism of Nano-Cu lubricating additives on the electroless deposited Ni-W-P coating

The coating and deposition process with excellent anti wear and suitable for industrial application were developed, and the optimum bath composition and process were obtained by studying the influence of the bath composition, temperature and pH value on the deposition rate and the plating solution stability. Moreover, the tribological properties of nano-Cu lubricating additives and electroless deposited Ni-W-P coating as well as their synergistic effect are researched using ring-block abrasion testing machine and energy dispersive spectrometer. Research results show that Ni-W-P alloy coating and nano-Cu lubricating additive have excellent synergistic effect, e g, the wear resistance of Ni-W-P alloy coating (with heat treatment and the oil with nano-Cu additives) has increased hundreds times than 45 steel as the metal substrate with the basic oil, and zero wear is achieved, which breaks through the bottleneck of previous separate research of the above-mentioned two aspects.