铸造碳化钨添加量对镍基复合喷熔涂层性能的影响

在镍基合金粉末NiCrBSi中添加不同比例的铸造碳化钨(WC),并采用氧乙炔火焰喷熔工艺在低碳钢表面制备了相应的Ni基WC复合涂层.采用金相显微镜观察了涂层的显微组织,采用湿砂橡胶轮式磨粒磨损试验机测试了涂层的抗磨粒磨损性能,并采用扫描电镜观察了喷熔粉末和喷熔层磨损后的形貌.结果表明:喷熔层的组织为在NiCr合金基体上弥散分布着不同粒度的碳(硼)化物硬质相;涂层的显微组织和WC的含量对Ni基WC喷熔层的硬度和抗磨损性能影响很大,涂层的硬度和抗磨损性能随WC添加量的增加先增加后减小;当WC的含量为35％时,Ni基体WC喷熔涂层的硬度最高,相应的抗磨粒磨损性能最好.     

碳化钨含量对高频感应熔覆涂层组织及性能的影响

采用高频感应熔覆的方法制备了两种不同碳化钨含量的镍基合金-WC复合涂层。采用扫描电子显微镜、X射线能谱仪和显微硬度计等对涂层的显微组织结构、成分和显微硬度进行了分析,通过磨损试验研究了不同WC含量涂层的耐磨性。试验结果表明,高频感应熔覆未产生剥落现象,在涂层与基体之间形成扩散结合层。10wt%的WC含量涂层的显微硬度和耐磨性能都要优于5wt%的WC含量的涂层。     

纳米WC增强Ni基合金喷熔层组织结构与抗磨粒磨损特性

目的研究纳米WC对Ni基合金喷熔层抗磨粒磨损性能的影响。方法采用扫描电镜、X射线衍射分析了氧乙炔火焰喷熔Ni基合金层和两种不同结构WC增强Ni基合金喷熔层的微观组织和相结构,并通过磨粒磨损试验平台对三种涂层进行磨损性能测试。结果纳米WC粉末的加入,能有效提高喷熔层的宏观硬度。通过组织分析得出纳米WC增强Ni基喷熔层中除含有γ-(Ni,Cr)固溶体、Cr的碳化物、硼化物以及微米级WC颗粒之外,还含有一定量的纳米WC团聚体和少量高硬度的W_2C相。磨粒磨损实验结果显示,纳米WC增强Ni基喷熔层的磨损失重分别为Ni60和NiWC35涂层失重的56%和73%。对比磨损后涂层的表面微观形貌可知,纳米WC颗粒在涂层中能有效降低磨粒压入喷熔层的深度,从而控制磨粒对喷熔层的犁削量。结论纳米WC增强Ni基合金喷熔层中含有的γ-(Cr,Ni)固溶体、Cr_(23)C_6、Cr_7C_3、Cr_3Ni_2及未熔化的WC颗粒和WC脱碳形成的W_2C等硬质相,使镍基自熔合金涂层的硬度有较大提高,同时也大大提高了涂层的抗磨粒磨损性能。     

导卫板失效分析及表面喷涂层的耐磨性能

对受高温磨损破坏的导卫板进行了失效分析，认为导卫板主要受到了疲劳磨损和磨料磨损。为提高导卫板的耐磨性，采用氧-乙炔火焰喷涂的方法在其磨损表面喷熔钴基WC涂层。实际应用表明，该喷熔层具有良好的耐磨效果，显著提高了导卫板的高温耐磨性。     

不同工艺条件下粗颗粒碳化钨金属陶瓷复合层的耐磨性研究

本文系统研究了激光熔覆粗颗粒WC金属陶瓷复合层的干砂磨粒磨损性能，并与氢原子堆焊粗颗粒WC管装焊条、氧乙炔焰堆焊粗颗粒WC复合焊条所得到的金属陶瓷复合层的耐磨性进行了对比。结果表明激光熔覆金属陶瓷复合层的耐磨性远远优于上述常规堆焊工艺。其主要原因是由于激光熔覆层中碳化钨颗粒烧损程度低与硬度高所致。     

不同工艺条件下粗颗粒碳化钨金属陶瓷复合层的耐磨性研究

本文系统研究了激光熔覆粗颗粒WC金属陶瓷复合层的干砂磨粒磨损性能，并与氢原子堆焊粗颗粒WC管装焊条、氧乙炔焰堆焊粗颗粒WC实心复合焊条所得到的金属陶瓷复合层的耐磨性进行了对比。结果表明激光熔覆金属陶瓷复合层的耐磨性远远优于上述常规堆焊工艺。其主要原因是由于激光熔覆层中碳化铝颗粒烧损程度低与硬度高所致。     

310S奥氏体不锈钢激光熔覆硬质合金复合涂层及其磨损性能研究

以镍粉和WC粉为原料,采用激光熔覆法在310S奥氏体不锈钢表面制备了镍基-WC复合涂层,研究了激光熔覆层的显微形貌、物相组成和耐磨性能,并分析了复合涂层的作用机理。结果表明,激光熔覆层致密,无气孔或者其它显微缺陷,熔覆层与基材冶金结合良好;Ni基-20%WC激光熔覆层的物相为:Ni_3Cr_2、Ni_(17)W_3、Cr_4Ni_(15)W、Fe_6W_6C、Mo_6Ni_6C、W3_C和WC;不同添加量的激光熔覆层的磨损失重均小于不锈钢基材,随着WC含量的增加,熔覆层的磨损失重量呈现逐渐降低趋势。     

WC含量对激光熔覆Ni基WC复合涂层组织和性能的影响

利用6 kW光纤激光器在Q235钢表面激光熔覆Ni基WC复合涂层。使用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射(XRD)、显微硬度计和磨损试验机,研究了不同WC颗粒含量下熔覆层组织形态、成分、显微硬度和磨损性能的变化规律。结果表明:熔覆层的稀释率随着WC含量的增加先减小后增加,当WC含量为20%时,稀释率最小。在光纤激光熔覆Ni基WC复合涂层的过程中,WC颗粒部分发生溶解并与其他元素相互作用形成共晶物,析出后分别以条状、块状和粒状等形态存在,随着WC含量的增加,熔覆层的组织出现细化现象。含WC的熔覆层组织中主要有γ-Ni、M_7C_3、M_(23)C_6、CrB、WC和W_2C等相存在。随着WC含量增加,熔覆层硬度增加,当WC质量分数达到40%时,熔覆层硬度可达到基体硬度的5倍以上。当WC的相对质量分数为20%时,熔覆层耐磨性能最好,耐磨性为Ni60A涂层的3倍以上。     

信息动态

在1Cr18Ni9Ti奥氏体不锈钢表面激光熔覆了Co基金属陶瓷复合涂层,对高温氧化后基体和复合层进行物相分析,并采用垂直气-砂喷射式高温冲蚀磨损试验装置进行高温冲蚀试验,分析熔覆层冲蚀后的微观形貌.研究表明:钴基合金熔覆层具有良好的抗高温氧化性能,原因在于Co能有效促进形成由Cr2O3,CoO·Cr2O3或CoCr2O4组成的致密氧化膜,且CoO与Cr2O3间较强的结合键增强了氧化膜的致密性.钴基合金添加10％ WC的激光熔覆层具有比基体金属更为优良的抗高温冲蚀磨损性能,而添加了20％ WC的激光熔覆层的抗高温冲蚀磨损性能则比基体差.     

激光熔覆Ni基微-纳米WC金属陶瓷涂层组织及干滑动磨损性能

在45钢表面进行添加微一纳米WC颗粒的镍基自熔粉末激光熔覆处理.得到不同Ni基WC合金涂层.对熔覆层进行显微组织观察、硬度测定以及室温千摩擦磨损试验.结果表明,纳米品WC的加入能改善涂层的耐磨性能,在本试验条件下,当添加的纳米级WC和微米级WC各为15%时.涂层耐磨性能最佳;但纯纳米晶WC增强涂层耐磨性不佳,其主要磨损破坏方式随涂层中WC晶粒尺寸变化而有所变化.     

Microstructure and Sliding Wear Resistance of Laser Cladded WC/Ni Composite Coatings with Different Contents of WC Particle

The aim of this article was to address the effect of WC content on the microstructure, microhardness, and sliding wear resistance of laser cladded WC/Ni composite coatings. The content of WC particle in the feed powder varied in the range of 0-80 wt.%. Experimental results showed that the laser cladded coatings exhibited homogeneous microstructure without pores or cracks. By comparing with the 45# steel substrate, the microhardness of WC/Ni composite coatings was relatively high. The microhardness of coating increased with increasing the content of WC particles. The wear resistance of WC/Ni composite coatings was strongly dependent on the content of WC particle and their microstructure. When the WC content was lower than 40 wt.% in the feed powder, the wear rate of the coatings decreased with increasing WC content. The two-body abrasive wear was identified as the main wear mechanisms. For the coatings with WC content higher than 40 wt.% in the feed powder, their wear rate increased with increasing WC content. The three-body abrasive wear and fatigue wear were the main failures. The coating with 40 wt.% WC in the feed powder exhibited the best wear resistance.     

等离子弧堆焊镍基球形碳化钨涂层摩擦磨损研究

目的采用等离子转移弧堆焊技术制成镍基球形碳化钨复合涂层,研究碳化钨含量对复合涂层摩擦磨损性能的影响,以用于实际生产开发。方法碳化钨质量分数分别为20%、30%、50%、60%的镍基混合粉末通过等离子堆焊方法制备成复合涂层,并采用Bruker公司生产的万能摩擦磨损试验机对镍基碳化钨复合涂层的侧面进行摩擦磨损性能测试。对各组涂层的表面形貌、摩擦系数、划痕横截面积及磨损面的微观形貌进行对比分析,探究碳化钨的含量对复合涂层摩擦磨损性能的影响。结果等离子转移弧堆焊镍基球形碳化钨复合涂层的耐磨性能随着碳化钨含量的增大而增大,同时近熔合区基体的耐磨性能也不断提高。当碳化钨质量分数小于50%时,主要发生的是粘着磨损和氧化磨损;当碳化钨质量分数大于50%时,主要发生的是粘着磨损和磨料磨损。结论由于碳化钨的存在以及增强相的不断生成,随着碳化钨含量的增大,复合涂层的磨损性能不断提高。出于性能和成本考虑,当碳化钨质量分数为50%时更适合实际应用。     

激光熔覆WC增强Ni基复合涂层的研究进展

激光熔覆是一种新型表面改性技术,具有能量密度高、稀释率可控、涂层与基体呈现良好的冶金结合等优点,且快热快冷的特性有利于在基材表面形成具有细小致密组织的涂层,从而获得耐磨耐蚀等优异性能.WC增强Ni基复合涂层因兼具陶瓷材料优异的耐高温、耐磨性和金属材料良好的强韧性,近些年成为激光熔覆研究领域的热点.综述了激光熔覆WC增强...     

20Cr2Ni4A钢表面WC增强铁基涂层耐磨性能的研究

目的 制备优异的耐磨性涂层用于机械零部件表面,可有效地提高其使用寿命,减少机械设备因磨损失效而带来的各类故障.方法 以20Cr2Ni4A合金钢为基体材料,利用激光熔覆技术,制备了铁基涂层和铁基/WC复合涂层.采用X射线衍射仪(XRD)、金相显微镜、扫描电子显微镜(SEM)、HV-1000显微维氏硬度计,分别对铁基涂层和铁基/WC复合涂层的相组成、组织形貌、显微硬度进行表征.利用HRS-2M型高速往复摩擦磨损试验机对铁基涂层和铁基/WC复合涂层的磨损性能进行研究,并分析其磨损机理.结果 两种涂层的显微硬度与基体相比改善较大,其中铁基/WC复合涂层改善最为明显,表面平均硬度值为610HV.以直径为6 mm的GCr15对磨球为摩擦副,铁基涂层的平均摩擦因数为0.53左右,磨损量为0.1432 mm3,而铁基/WC复合涂层的平均摩擦因数为0.36左右,磨损量为0.05935 mm3,与铁基涂层相比,20Cr2Ni4A合金钢表面结合铁基/WC复合涂层的硬度提高了17％左右,磨损量减小了58.6％,具有良好的耐磨损性能.结论 铁基/WC复合涂层因其表面存在W2C、WC、Fe3C等物相,能够均匀分布在铁基涂层上作为耐磨骨架,显著提高了涂层的硬度和耐磨性能.     

High temperature wear resistance and thermal fatigue behavior of Stellite-6/WC coatings produced by laser cladding with Co-coated WC powder

The Stellite-6/WC composite coatings were produced on AISI H13 hot work tool steel by laser cladding with mixture of Co-coated WC (WC-12Co) particles and Stellite-6 powder. The phase composition, microstructural characterization, high temperature wear resistance and thermal fatigue behavior of Stellite-6/WC coatings were investigated and compared with the properties of the coatings produced from mixture of WC particles and Stellite-6 powder. The results showed that using the WC-12Co particles alleviated the decomposition of WC and resulted in the weaker intensity of W₂C, CoC_x and Co₆W₆C peaks in the X-Ray Diffraction (XRD) patterns. Compared with using the WC particles directly as the coating material, using the WC-12Co particles could further improve the wear resistance of coatings according to the relative lower width and depth of wear scars at the same WC content. In addition, fewer fatigue cracks were observed on the surface of coatings made by adding WC-12Co particles under the same thermal fatigue conditions, which indicates that using WC-12Co is beneficial to extend the life of Stellite-6/WC coatings.     

Characteristics of Fe-based WC Composite Coatings Prepared by Double-pass Plasma Cladding Process

The Fe-based WC composite coatings were clad on Q235 steel by double-pass plasma cladding method,in which the WC-Co(WC covered with cobalt:78wt%WC,12wt%Co)doping was about 10wt%,20wt%and 40wt%,respectively.The microstructure and wear performance of the composite coatings were investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and ball-disc wear tests.The results show that the clad coatings contain mainly?-Fe,WC and carbides(Cr23C6,Fe3W3C-Fe4W2C)phases and the precipitation of carbides increases with the increase of WC-Co doping content.The WC-Co doping content has an obvious effect on the microstructure of the clad coatings.For the clad coatings with low WC-Co doping,the microstructure gradually transforms from planar crystal at the interface of substrate/coating to cell/dendritic crystal at the middle and the upper portion of the coatings.But there are a number of fishbone-like structure at the middle and the upper portion of clad coating with 40wt%WC-Co doping.The microstructure at the top is smaller than that at the bottom for all the coatings.The maximum of hardness of the clad coatings is 72.3HRC which is about 6.9 as much as the hardness of Q235 steel substrate.The composite coatings have good wear resistance due to the reinforcement of carbide particles and the strong bonding between carbide particles and ferroalloy.The suitable increase of WC-Co doping content can improve the wear resistance of the composite coatings.     

Microstructure and properties of WC reinforced Ni-based composite coatings with Y2O3 addition on titanium alloy by laser cladding

ABSTRACT

In this study, WC reinforced Ni-based composite coatings with Y₂O₃ addition were deposited on Ti-6Al-4V titanium substrate by laser cladding. The phases, microstructure, microhardness and wear resistance of the composite coatings were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, microhardness tester and wear tester. The results showed that good metallurgical bonding was achieved between the composite coatings and substrate. The phases mainly were γ-Ni, TiC, TiB₂, Ni₃B, M₂₃C₆ and WC. Most of the WC was dissolved in small pieces of WC during the laser cladding process. The microhardness of the composite coatings was about 3 times that of the titanium substrate and the wear resistance of the composite coatings had a significant increase.     

Improvement of wear resistance of wire drawing rolls with Cr-Ni-B-Si + WC thermal spraying powders

In wire drawing process, wear of rolls must be considered because of wear that influences the economics of the forming process. In this study, a nickel based matrix reinforced with WC was deposited by low cost powder welding method on low carbon steel substrates in order to determine the wear resistance of wire drawing rolls. Powder welding method includes, contrary to plasma and high velocity oxyfuel (HVOF) spraying methods, the advantages such as the single operation of powder application-fusion, simplicity, cheapness, and the ease of application. Blends of NiCrBSi and WC powders were prepared in weight proportions of WC of 40%, 45%, 50%, 55%, and 60%, respectively. Wear performance of these coatings was investigated by the dry sliding wear experiments. The wear resistance of the metal matrix composite coatings is dependent on the amount of WC. From 40% to 60%, the increase of WC is very effective on the wear resistance. The coatings with 55% and 60% of WC were worn less than the other coatings. From 55% to 60%, further increase of WC was found not to be effective for the best wear resistance. The microscopic studies of WC particles and Ni-based matrix were characterized by the scanning electron microscopy (SEM). The SEM analysis on the worn surface of coated samples shows that the matrix is considerably worn while WC particles are not considerably worn at the beginning of the wear testing. Additionally, WC particles effectively provide protection for achievement of the wear resistance at advanced periods of the wear testing.     

La_2O_3稀土对激光熔覆WC/Ni基复合涂层性能改善的研究

向WC陶瓷镍基合金粉末中添加不同质量分数的La2O3粉末制成混合粉末,采用大功率半导体激光器通过同轴送粉方式,在A3钢基材上制备熔覆层。利用SEM、EDAX、XRD分析研究了不同稀土加入量对熔覆层显微组织和相结构的影响,用显微硬度计、滑动摩擦磨损试验机分别测试了复合涂层的硬度、耐磨性。结果表明:由于稀土的加入,复合涂层的晶粒进一步细化,组织趋向均匀,硬度和耐磨性得到了提高,最终得出涂层粉末的最佳配比为(质量分数)59%Ni60,40%WC,1.0%La2O3。     

WC对激光熔覆层组织及耐磨耐冲击性的影响

激光熔覆Ni基合金涂层具有良好的综合性能,但耐磨与耐冲击性能仍有待提高。分别采用含微米与纳米WC颗粒的Ni基粉末激光熔覆制备WC/Ni涂层,研究两种WC颗粒对Ni基涂层组织及耐磨耐冲击性的影响。利用SEM与XRD对涂层进行微观组织分析,利用高速摄像机分析熔覆过程中的熔池形态。采用磨损试验机、夏比冲击试验机对涂层进行耐磨性与耐冲击性测试。纳米WC对熔池流动的促进作用强于微米WC,并使涂层组织得到更显著的细化。由于微米WC与Ni45涂层结合紧密,磨损试验中能有效抵抗配磨件微凸体的切削,最终显著增强涂层耐磨性,磨损率较Ni45涂层降低88.38%。但微米WC的高脆性不利于涂层耐冲击性的提高,冲击韧性仅为Ni45涂层的91.28%。由于纳米WC在细化晶粒的同时会弥散分布于晶界与共晶区,在磨损过程中阻碍位错运动,抑制晶粒塑性变形,进而减弱配磨件对涂层的切削,提高涂层耐磨性,磨损率较Ni45涂层降低53.43%。由于在晶界与共晶区的纳米WC会阻碍裂纹扩展并改变扩展方向,进而提高形成贯穿裂纹的能量,增加涂层断裂所需的冲击功,使涂层耐冲击性得到显著提高,冲击韧性较Ni45涂层提高13.37%。通过有限元分析可知,在冲击过程中涂层中的高脆性微米WC会形成高应力集中,证明其对涂层耐冲击性具有不利影响。而纳米WC能降低位错的不均匀滑移,缓解位错堆积,进而有效分散涂层在冲击过程中形成的应力集中,证明其能显著提高复合涂层的耐冲击性能。研究证明,纳米WC能实现涂层耐磨性与耐冲击性的同步提升。