不同碳化钨含量对等离子弧熔覆镍基碳化钨涂层组织及性能的影响

采用等离子弧粉末熔覆技术在Q345钢表面熔覆镍基碳化钨涂层,研究了粉末中不同碳化钨含量对镍基碳化钨熔覆层组织及性能的影响.借助光学显微镜、扫描电镜及X射线衍射仪分析镍基碳化钨熔覆层的组织形貌,用显微硬度计和摩擦磨损实验机分别测量镍基碳化钨熔覆层的硬度和耐磨性.结果表明:镍基碳化钨熔覆层与基层之间呈冶金结合,涂层表面无气孔缺陷.镍基碳化钨涂层组织主要由碳化钨颗粒和镍基粘结相构成,碳化钨是WC和W2 C,镍基粘结相中包含SiC、Cr23 C6 、Ni3 Si、γ-Ni等物相.随着粉末中碳化钨含量从15% (质量分数,下同)增加至50% ,熔覆涂层组织中硬质相数量增多,其硬度和耐磨性显著提高.当碳化钨含量为50%时,熔覆涂层硬度高达1 024HV10且耐磨性最好.     

合金成分对镍基合金激光熔覆涂层组织与性能的影响

为了研究激光熔覆镍基合金涂层显微组织与性能之间的关系,本文选用Ni25、Ni45、Ni60镍基自熔性合金粉末作为熔覆材料,在同一工艺参数下在45#钢基体上制得Ni25、Ni45、Ni60合金激光熔覆涂层。利用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、显微硬度计等方法对涂层的显微组织、物相组成、显微硬度等进行了研究。结果表明从Ni25到Ni60合金涂层,随着合金元素含量的提高,涂层微观组织逐渐由亚共晶转变为过共晶,γ-Ni奥氏体枝晶所占体积分数减少,尺寸细化,枝晶间的共晶组织和硬质相所占的体积分数增大,涂层和基体之间结合带的宽度越来越窄,熔覆层的显微硬度越来越高。Ni25、Ni45合金涂层的平均显微硬度分别为250HV和550HV左右,而Ni60合金涂层的平均硬度却高达750HV左右,为Ni25合金涂层的3倍。     

Ti811表面激光熔覆原位合成TiC-TiB2复合Ti基涂层的微观组织分析

在Ti811钛合金表面利用同步送粉激光熔覆技术,制备了TC4+Ni45多道搭接激光熔覆层。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱分析仪(EDS)等分析了涂层组织和相组成,利用显微硬度计测试了涂层的显微硬度。结果表明,涂层微观组织中均匀分布的析出相主要包括基底α-Ti、金属间化合物Ti_2Ni、增强相TiB_2和增强相TiC。其中,TiC在TiB_2表面异质形核,形成了TiC+TiB_2的复合相结构;同时,纳米TiC颗粒在涂层基体中弥散分布。由于涂层中TiC与TiB_2的共同作用,涂层的显微硬度与基底相比有了显著提高,最高硬度为770HV0.5左右,约为基底硬度的2倍。     

激光熔覆Fe60Nb20Ti20非晶合金粉末及组织性能研究

采用激光熔覆工艺在45钢表面对Fe60Nb20Ti20非晶合金粉末进行不同工艺参数熔覆试验,获得无裂纹且呈冶金结合的涂层。利用扫描电镜、X射线衍射仪、显微硬度计、摩擦磨损试验机对涂层的微观形貌、组成相、显微硬度和摩擦磨损性能进行分析。结果表明,涂层组织为细小的α-Fe过饱和固溶体等轴晶和少量的非晶相。涂层平均硬度为857HV,为基体材料的4倍,耐磨性也明显优于基体材料。     

激光熔覆法制备Al2O3-TiO2涂层的显微组织与性能研究

采用预置粉末式激光熔覆法在钛合金(Ti-6Al-4V)表面开展了Al_2O_3-13%(质量分数)TiO_2涂层的研究。利用光学显微镜(OM)、扫描电子显微镜(SEM)、X射线衍射分析仪(XRD)和显微硬度计研究了激光熔覆熔池的特征和涂层的显微结构,分析了涂层的成分分布、相组成和显微硬度分布情况。预置粉末激光熔覆制备的Al_2O_3-13%(质量分数)TiO_2涂层界面结合良好,涂层组织均匀,没有明显的裂纹和气孔。激光熔覆涂层表现出明显流线型特征,熔覆层截面分为热影响区、扩散结合区和涂层区。涂层由Ti、AlTi_3、α-Al_2O_3和γ-Al_2O_3等相组成。涂层的显微硬度达到1000~1300HV_(0.3),比基体硬度360~390HV_(0.3)高2倍。     

钛合金表面激光熔覆Ni基梯度涂层的研究

为了改善Ti6Al4V钛合金表面耐磨性能和抗高温氧化性能,采用CO2激光在Ti6Al4V钛合金表面进行激光熔覆Ni基梯度涂层试验.利用扫描电镜和显微硬度计等手段分析了熔覆层组织,测试了基体和熔覆层的显微硬度.结果表明,采用适当的工艺参数,可以在钛合金表面获得连续、均匀、无裂纹和气孔的熔覆层.熔覆层组织由树枝晶和晶间共晶组织构成,并与基体形成牢固的冶金结合.由基体到表面,显微硬度过渡平稳,呈明显梯度渐变特征.     

Ti811合金表面激光熔覆Ti2Ni+TiC+Al2O3+CrxSy复合涂层的组织和性能

以TC4+Ni45+Al₂O₃+MoS₂+Y₂O₃混合粉末为熔覆材料,采用同轴送粉技术在Ti811合金表面进行激光熔覆制备复合涂层,使用SEM、EDS和XRD等手段分析了涂层的微观组织,测试了涂层的显微硬度和摩擦磨损性能。结果表明,在激光熔覆过程中Ti811合金中的Ni和C分别与Ti发生反应,原位生成金属间化合物Ti₂Ni和硬质增强相TiC;MoS₂分解后S与Cr发生硫化反应生成了软质润滑相Cr_xS_y。网状形态的Ti₂Ni、近球状和枝晶形态的TiC以及点状的Al₂O₃,均匀分布在熔覆层中。硬质相强化和软质相润滑的共同作用,使激光熔覆层具有较高的显微硬度和较优良的耐磨性能。激光功率为900 W的熔覆层其平均显微硬度值达1303.5HV_0.5,其耐磨性能最佳。     

激光熔覆制备Ni60−WC−Co复合涂层工艺与性能研究

目的 提高机械设备用06Cr19Ni10钢的性能,采用激光熔覆制备Ni60?WC?Co复合涂层。方法 利用X射线衍射(XRD)、扫描电镜(SEM)、显微维氏硬度计和摩擦磨损试验仪,研究了不同激光功率对复合涂层的微观形貌、硬度和耐磨性的影响。结果 随着激光功率增大,复合涂层与基体之间紧密结合,致密均匀,球形WC颗粒均匀分布于复合涂层中,硬度、磨损量均先增大后减小;当激光功率过大时,复合涂层中WC颗粒增多,且部分WC颗粒发生热分解,生成的气体产生气孔。复合涂层物相主要由WC、W2C、γ?Ni、FeNi3、FeCr0.29Ni0.16C0.06、CoCx、Co3B2等相组成,复合涂层由顶部的树枝晶、中部的等轴晶和底部的柱状晶组成;当激光功率为1.5 kW时,硬度最高,磨损量最小,耐磨性最佳,磨损表面无明显磨损沟槽,主要呈磨粒磨损。结论 最优激光功率为1.5 kW,在此工艺下制备的Ni60?WC?Co复合涂层,可以提高机械设备用06Cr19Ni10钢的硬度和耐磨性。     

激光熔覆Al-Ni-TiC-CeO2复合涂层的组织与耐腐蚀磨损性能

采用激光熔覆技术在S355海洋钢表面制备Al-Ni-TiC-CeO2熔覆涂层,通过SEM、EDS、XRD、显微硬度计等手段分析其表面-界面形貌、化学元素分布、物相组成及显微硬度,并研究其在3.5%(质量分数)NaCl溶液中耐腐蚀磨损与应力腐蚀开裂(stress corrosion cracking,SCC)等性能。结果表明:熔覆涂层主要由增强相TiC和连续相AlNi3,AlFe3组成,表面较为平整,无明显裂纹,稀释率为5%。涂层表面显微硬度达到809.3HV0.2,为基体的2.3倍。基体中交互作用主要以腐蚀加速磨损为主,而涂层中交互作用则以磨损加速腐蚀为主。基体材料与涂层的SCC敏感性分别为35.01%和17.69%,表明涂层能够明显抑制应力腐蚀开裂。     

等离子熔覆铁基非晶纳米晶复合涂层及其性能

利用等离子熔覆技术在A3钢表面制备了一层与基体呈冶金结合的、性能良好的非晶纳米晶复合涂层.涂层有非晶相和纳米相组成,根据衍射峰的半高宽,计算出铁基涂层中平均晶粒尺寸为22～24nm.对涂层进行XRD、SEM、EDS、TEM和DSC分析,并利用显微硬度计和电化学工作站研究涂层的硬度和耐蚀性能,研究表明所制备的铁基涂层具有良好的性能.     

爆炸喷涂纳米WC-Co涂层的研究

为促进爆炸喷涂法替代常规喷涂工艺在工业上的应用,采用爆炸喷涂法制备了纳米和普通WC-12Co涂层.采用金相显微镜、扫描电镜分析比较了两种涂层的显微组织,用显微硬度计和磨料磨损试验机测试了两种涂层的显微硬度及耐磨料磨损性能,并利用扫描电镜对磨损形貌进行了分析.结果显示,纳米涂层具有比普通涂层更高的致密度和显微硬度,纳米涂层中WC颗粒的分布更均匀;纳米涂层的磨损机理为微观切削机制,其耐磨料磨损性能比普通涂层差.     

Microstructure and property of Ni60A/WC composite coating fabricated by fiber laser cladding

Laser clad Ni60A/WC composite coating was fabricated on the surface of Q235 steel by using 6 kW fiber laser. The morphology, composition, and microhardness of composite coating were studied by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X‐ray diffraction (XRD), and micro‐hardness tester. The results show that in the process of fiber laser cladding Ni60A/WC composite coating, residual WC particles partially dissolve and react with other elements to form eutectics, which exists in the shape of lumpy, strip and spherical. The main structures of laser cladding are γ‐Ni, WC, W₂C, M₇C₃, M₂₃C₆ etc. From the hardness analysis, the average hardness of the composite coating is four times of the substrate.     

Homogenization of Carbides in Ni60/WC Composite Coatings Made by Fiber Laser Remelting

In the current study, the effect of laser remelting on homogenization of carbides in WC-reinforced Ni60 composite coatings was investigated. Ni60 + 50 wt% WC composite coatings were fabricated on the surface of Q550 steel by LDF4000-100 fiber laser device. First cladding layer was made by rectangle laser spot and then circular laser spot was utilized to remelt the coatings. Microstructure characteristics were investigated by optical microscope and scanning electron microscopy. Elemental distribution and phase constitution were analyzed by energy disperse spectroscopy and X-ray diffraction. The results showed that accumulation of residual WC particles was sufficiently eliminated under the effect of laser remelting. The irregularly shaped carbides in first cladding layer were transformed into well-distributed polygonal carbides by laser remelting. Statistical analysis indicated median size of reinforcement particles decreased from 35.40 to 5.62 µm. Microhardness of remelted region had a smooth profile and decreased by ?50 HV_0.1 than that of first cladding region. Homogenization of carbides in nickel composite coating was well realized by laser remelting.     

硬质相对冷喷涂FeAl金属间化合物涂层性能的影响

FeAl金属间化合物具有优良的物理性能和力学性能,但其室温塑性和断裂韧性低,限制了其工程应用.利用机械合金化制备了Fe(Al)固溶体合金粉末及Al2O3,WC硬质相增强的复合合金粉末,通过冷喷涂沉积涂层并结合后热处理原位反应制备了FeAl金属间化合物涂层及其复合涂层.利用扫描电镜(SEM)、X射线衍射仪(XRD)及显微硬度仪等研究了硬质相对球磨粉末组织结构、冷喷涂FeAl金属间化合物涂层组织结构及性能的影响.结果表明.硬质相可显著加速球磨粉末内部层状结构的细化程度,喷涂态涂层具有不同于传统热喷涂涂层的层状组织结构,热处理可实现喷涂态涂层中Fe(Al)固溶体向FeAl金属间化合物的原位转变,致使层状结构消失,获得无粒子界面的FeAl金属间化合物涂层,弥散分布的硬质相可显著提高冷喷涂FeAl金属间化合物涂层的强化稳定性.     

纳米金刚石复合镀层制备工艺的研究

纳米金刚石复合镀层具有金刚石和纳米颗粒的双重特性,应用前景广阔.采用复合电镀法制备了Ni-纳米金刚石复合镀层,考察了阴极电流密度、镀液pH值以及搅拌强度对纳米复合镀层显微硬度的影响,并分析了Ni-纳米金刚石复合镀层的共沉积过程.结果表明,选择适当的共沉积工艺参数,可以制备出同底材结合牢固,金刚石微粒弥散较均匀的高硬度纳米复合镀层,基质Ni中金刚石粒子的含量与镀面的机械俘获粒子的能力有关.     

钢表面颗粒增强熔覆层的组织和性能

采用预置法在45号钢表面制备WC颗粒增强熔覆层,研究了熔覆层的组织和性能,并与淬火态Cr12MoV(59HRC)的耐磨性能进行比较,分析磨损机理并讨论WC颗粒的磨损现象。结果表明:熔覆层与基材之间结合良好并形成界面反应层;熔覆层组织分布均匀,表面弥散分布着大量WC颗粒;熔覆层的平均硬度比基材的高,耐磨性是基材45号钢的18倍,是淬火态Cr12MoV的2倍;在磨损实验中熔覆层的增强颗粒WC出现罕见的表面磨平和脆性脱落现象。     

NAK80模具钢表面2种激光器熔覆Ni基碳化钨合金层组织结构及耐磨性比较

为了研究激光器对Ni基碳化钨合金熔覆层组织结构和性能的影响,分别采用Nd:YAG与CO2激光熔覆技术在NAK80模具钢表面制备了Ni基碳化钨合金层,利用X射线衍射仪(XRD)、扫描电镜(SEM)、能谱仪、显微硬度计以及摩擦磨损试验机测试分析了2种熔覆层的组织结构、显微硬度及耐磨性能。结果表明:2种熔覆层与基体之间均呈现良好的化学冶金结合;熔覆层组织主要为粗大的未熔碳化钨颗粒和均匀分布的树枝晶,Nd:YAG激光熔覆层的组织比CO2激光熔覆层的细小;2种熔覆层相结构主要包括WC,W2C,Cr23C6,NiCr,CrB2以及γ-Ni等;2种激光器熔覆处理后,NAK80模具钢表面硬度和耐磨性都得到显著改善,CO2激光熔覆层的硬度和耐磨性高于Nd:YAG激光熔覆层,2种激光熔覆试样的磨损机制均为磨粒磨损。     

Laser surface coating of Mo–WC metal matrix composite on Ti6Al4V alloy

Laser surface alloying of Mo, WC and Mo–WC powders on the surface of Ti6Al4V alloys using a 2 kW Nd-YAG laser was performed. The dilution effect upon the microstructure, microhardness and wear resistance of the surface metal matrix composite (MMC) coating was investigated. With a constant thickness of pre-placed powder, the dilution levels of the alloyed layers were found to increase with the incident laser power. The fabricated surface MMC layer was metallurgically bonded to the Ti6Al4V substrate. The microhardness of the fabricated surface layer was found to be inversely proportional to the dilution level. The EDAX and XRD spectra results show that new intermetallic compounds and alloy phases were formed in the MMC layer. With the existence of Mo content in the pre-placed powder, the β-phase of Ti in the MMC coating can be retained at the quenching process. With increasing weight percentage content of WC particles in the Mo–WC pre-pasted powder, the microhardness and sliding wear resistance of the laser surface coating were increased by 87% and 150 times, respectively, as compared with the Ti6Al4V alloy. The surface friction of the laser-fabricated MMC coatings was also decreased as compared with the worn Ti6Al4V substrate.     

Characterization of Gradient Ni-Fe/SiC Composite Coating on Mild Steel by Thermal Spraying in Combination with Laser Cladding

0 IntroductionMetal matrix composites(MMCs)can usuallyprovide a high stiffness to weight ratio and high wearresistance,and a material with a surface MMC hasthe potential to develop these properties on its sur-face[1].And laser cladding has been found to be anefficient technique to prepare MMC coatings on thesubstrates such as Al-based alloy,steel,brass andbronze[2~4].Among various MMC coatings preparedby laser cladding,those reinforced with oxides(mainly Al2O3)and carbides(TiC,SiC,B4C,…     

W6Mo5Cr4V2高速钢WC/Co激光熔覆表面的摩擦磨损性能

为了改善高速钢表面的摩擦磨损性能,应用激光熔覆技术在W6Mo5Cr4V2高速钢表面制备出WC/Co熔覆道。采用三维数码显微镜观察熔覆试件的金相组织并借助显微硬度计测试其显微硬度。采用销盘式摩擦磨损试验机分别对高速钢和WC/Co熔覆试件进行了摩擦磨损试验,并采用三维数码显微镜观察磨损形貌。结果表明:与高速钢基材相比,WC/Co熔覆道硬度提高,熔覆试件的摩擦系数和磨损量降低;WC/Co熔覆道的磨损机制以磨粒磨损为主,熔覆道间隔以磨粒磨损和黏着磨损为主;熔覆道的硬度提高、减摩效果、散热作用以及试件表面熔覆道与间隔面的软硬交替,有助于提高WC/Co熔覆试件的摩擦磨损性能。