氧乙炔火焰喷焊镍基复合涂层的显微组织和腐蚀性能研究

目的 研究Ni60和Ni60WC喷焊涂层的显微组织、防腐和耐磨性能及其腐蚀机理,为恶劣工况下服役的零件选择合适的喷焊涂层提供参考.方法 采用氧乙炔火焰喷焊工艺在16Mn钢基体上制备Ni60和Ni60WC涂层,用X射线衍射仪、金相显微镜和扫描电子显微镜分析了喷焊涂层的相结构和显微组织,并采用电化学工作站、盐雾腐蚀试验机、磨粒磨损试验机测试了两种喷焊涂层的防腐和耐磨性能.结果 喷焊层与基体间都存在冶金结合层和热影响区,Ni60涂层的显微组织为NiCr固溶体基体上弥散分布着大量细小粒状和杆状碳化物和硼化物.Ni60WC喷焊涂层组织中,除了具有与Ni60涂层类似的基体相和细颗粒硬质相外,还较均匀地分布着不同尺寸的WC颗粒.Ni60和Ni60WC涂层的磨损率分别为16Mn钢的8.3％和2.3％,自腐蚀电流密度分别为16Mn钢的1.0％和7.6％.另外,基体相和硬质相之间的电偶腐蚀是两种镍基喷焊涂层的主要腐蚀机理.结论 这两种镍基喷焊涂层均能显著提高16Mn钢的抗磨和防腐性能,其中,Ni60喷焊涂层耐腐蚀性更好,Ni60WC喷焊涂层耐磨损性能更好.     

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。     

高Ni钎料-WC硬质合金颗粒复合堆焊焊条的探讨

以SiC材质成型舟皿作为模具,尺寸为2～5 mm的YG8型WC硬质合金颗粒为耐磨相,CuZnNi合金为胎体金属,加入NiCrBSi合金粉末以提高胎体金属的Ni含量与Cr含量,采用钼丝氢气炉烧结制备高Ni钎料-WC硬质合金颗粒复合堆焊焊条,并对成型后焊条的断面形貌及胎体金属成分进行分析.结果 表明,硬质合金颗粒在焊条内呈...     

Effect of flame conditions on abrasive wear performance of HVOF sprayed nanostructured WC-12Co coatings

Nanostructured WC-12Co coatings were deposited by high velocity oxy-fuel (HVOF) spraying with an agglomerated powder. The effect of flame conditions on the microstructure of the nanostructured coatings was investigated. The wear properties of the coatings were characterized using a dry rubber-wheel wear test. The results show that the nanostructured WC-Co coatings consist of WC, W2C, W and an amorphous binder phase. The microstructure of the coating is significantly influenced by the ratio of oxygen flow to fuel flow. Under the lower ratio of oxygen/fuel flow, the nanostructured coating presents a relative dense microstructure and severe decarburization of WC phase occurs during spraying. With increasing ratio of oxygen/fuel flow, the bonding of WC particles in the coating becomes loose resulting from the original structure of feedstock and the decarburization of WC becomes less owing to limited heating to the powder. Both the decarburization of WC particles in spraying and the bonding among WC particles in the coatings affect the wear performance. The examination of the worn surfaces of the nanostructured coatings reveals that the dominant wear mechanisms would be spalling from the interface of WCCo splats when spray particles undergo a limited melting. While the melting state of the spray particles is improved,the dominant wear mechanisms become the plastic deformation and plowing of the matrix and spalling of WC particles from the matrix.     

等离子熔覆添加和内生联合WC颗粒增强铁基涂层的组织和性能

采用等离子熔覆技术,以铸造碳化钨、钨铁粉、镍包石墨和铁基合金粉为原材料,在Q235钢基体上制备了外加和内生联合WC颗粒增强铁基复合涂层,通过扫描电镜和能谱分析、X射线衍射、硬度测试和磨料磨损试验对其微观组织、物相组成、硬度和耐磨性能进行了表征。结果表明,在优化的工艺参数下,可以获得与基体冶金结合良好的涂层,硬质相除外加的WC颗粒,还有内生的WC、W₂C、W₃C、Fe₃W₃C和Fe₂W₂C等;随着混合粉末中除外加WC之外的W含量增加,熔池中合金液密度增大,可以减弱外加WC颗粒下沉;当W含量达到15%时,外加WC颗粒均匀分布在涂层中,没有团聚现象发生,且在外加WC颗粒周围有细小的原位WC颗粒生成,涂层的显微硬度和耐磨损性能显著提高,涂层的平均硬度约为1300 HV0.2,耐磨性为Q235钢基体的10倍。     

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.     

电冶熔铸WC/GCr15钢复合材料的摩擦磨损特性

选择大颗粒WC作增强相，采用电冶熔铸工艺制备了含27％WC粒子的WC／GCr15钢复合材料，观察了复合材料中WC颗粒与钢基体的结合情况；在MM-200型摩擦磨损试验机上研究了室温下复合材料同GCr15钢对摩时的摩擦磨损性能。结果表明：复合材料中的WC颗粒部分溶解于钢基体相，两相界面形成厚达数微米的反应层，有效地提高了界面结合强度。电冶熔铸WC／钢复合材料的耐磨性能比基体材料GCr15钢提高了5倍以上，扫描电镜下的磨痕照片显示：大颗粒WC承担了磨损的主要载荷，实验中没有发生明显脱落的现象，说明界面结合强度在提高复合材料磨损性能方面所起的作用。     

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。     

Microstructures and mechanical properties of FeCoCrNi high entropy alloy/WC reinforcing particles composite coatings prepared by laser cladding and plasma cladding

FeCoCrNi HEA coatings with 20% mass fraction of WC reinforcing particles were prepared by two different cladding methods, laser cladding (LC) and plasma cladding (PC). The microstructure of HEA matrix and WC particles of LC and PC coatings were discussed respectively. For HEA matrix, dendritic morphology was observed in both coatings. For WC particles, a few granular (Cr,W)₂C carbides around WC particles in LC coatings, and a large number of crystal and fishbone Fe₃W₃C carbides around WC particles in PC coatings. Mechanical properties as hardness and wear resistance of the two kinds of coatings were also investigated. The interstitial solution strengthening effect of C element is stronger in PC coating, and the hardness of HEA matrix in LC coatings is twice that of in PC coating, which shows a strong retention force on WC particles. The friction coefficient of LC coating is lower and stable, with the volume wear rate of 0.7 × 10⁻⁵ mm⁻³/N·m, showing high wear resistance. PC coatings have poor wear resistance due to decarbonization and oxidation of WC particles and reduction of retention force of HEA matrix, with the volume wear rate of 8.29 × 10⁻⁵ mm⁻³/N·m. The wear mechanism of both coatings were also discussed.     

Tribological characteristics of WC-based claddings using a ball-cratering method

Tungsten carbide-based thick coatings are used as wear resistant claddings or surface overlays in industrial applications to counter erosive and/or abrasive wear problems. Three-body abrasive wear behaviour of infiltration brazed tungsten carbide (WC) claddings was investigated using a ball-cratering method, a version with a free ball, with slurry containing 150–300 μm silica sand particles. Three WC claddings tested had different volume fractions and size distribution of carbides that resulted in their different bulk hardness and the matrix was a Ni–Cr based alloy. It was found that the wear rates of all WC claddings were almost constant with testing time or distance travelled by a rotating ball. The wear rates were independent of the slurry delivery rate and did not increase with increasing rotating ball roughness. The wear rates were affected by the material characteristics of WC claddings such as the volume fraction of carbides, directly related to bulk hardness, and carbide size distribution. SEM examination found that three-body rolling wear was a dominating wear mechanism. The softer matrix was worn out preferentially, leaving behind protruding and weakly-supported carbides. Small solid carbides were then dislodged and larger cemented WC/Co carbides were gradually worn out by a combination of microcracking and attrition.The abrasive characteristics of WC claddings in the ball-cratering tests were then compared to the characteristics of nominally identical materials in the standard ASTM G65 and G76 tests, as reported in the literature, and similarities and differences found are reported. Also, the in-field wear mechanisms found in the WC cladding were compared to the mechanisms observed in the ball-cratering tests.     

Influence of WC addition in Co-Cr-W-Ni-C flame sprayed coatings on microstructure, microhardness and wear behaviour

In present paper the influence of the tungsten carbide (WC) particle addition on the microstructure, microhardness and abrasive wear behaviour of flame sprayed Co-Cr-W-Ni-C (EWAC 1006) coatings deposited on low carbon steel substrate has been reported. Coatings were deposited by oxy-acetylene flame spraying process. Wear behaviour of coatings was evaluated using pin on flat wear system against SiC abrasive medium. It was observed that the addition of WC particle in a commercial Co-Cr-W-Ni-C powder coating increases microhardness and wear resistance. Wear behaviour of these coatings is governed by the material parameters such as microstructure, hardness of coating and test parameters (abrasive grit size and normal load). Addition of WC in a commercial powder coating increased wear resistance about 4-9 folds. WC modified powder coatings showed better wear resistance at high load. Heat treatment of the unmodified powder coatings improved abrasive wear resistance while that of modified powder coating deteriorated the wear resistance. SEM study showed that wear of coatings largely takes place by microgroove, crater formation and scoring. Electron probe micro analysis (E.P.M.A.) of unmodified and WC modified powder coating was carried out for composition and phase analysis.     

等离子喷焊镍基合金耐磨性能研究

采用等离子弧喷焊技术在不同转弧电流下喷焊DG.Ni60A和DG.Ni60WC25两种镍基合金粉末,对各喷焊层进行了硬度和耐磨性分析。试验结果表明,转弧电流大小对喷焊镍基合金层的耐磨性影响较大,喷焊DG.Ni60A合金粉末时,转弧电流为100 A时的试样磨损量为0.090 57 g,转弧电流为150 A时的试样磨损量高达1.116 17 g,相差10余倍。喷焊DG.Ni60WC25合金粉末时,转弧电流为100 A时的磨损失质量仅为0.018 83 g,转弧电流为200 A时的磨损失质量高达0.744 97 g,相差约40倍。镍基合金中加入WC,在一定条件下可以提高喷焊层的耐磨性能;转弧电流为150 A时,未添加WC硬质相的DG.Ni60A合金粉末喷焊层的磨损失质量高达1.116 17 g,而添加了WC硬质相的DG.Ni60WC25合金粉末磨损失质量为0.018 83～0.744 97 g。     

火焰喷涂碳化物涂层的耐磨性研究

对碳化物复合粉末热喷涂工艺和Ni基自熔合金粉末热喷焊工艺进行了研究，在低碳钢基体上分别采用氧-乙炔火焰喷涂Co包WC粉末、Ni包WC粉末，以及火焰喷焊Ni60、Ni60 20％WC自熔合金工艺获得耐磨合金涂层。研究了涂层的显微结构和相特征以及耐磨性。结果表明，在喷焊Ni60 20％WC粉末涂层的组织中，由于加入了WC粒子，有效改善了涂层的显微组织和性能，得到了喷焊质量和耐磨性俱佳的合金涂层。     

等离子弧堆焊铁基熔覆层组织结构与磨损行为

设计开发了一种铁基(含Cr,Mo,C,B,Si,Mn等元素)多元合金粉末,采用等离子弧堆焊(PTAW)技术在AISI304L不锈钢表面制备相应熔覆层,通过XRD,SEM,EDS及磨粒磨损试验机等对熔覆层微观组织结构和磨损行为等进行表征,并与传统NiCrBSi和NiCrBSi+25%WC粉末的PTAW熔覆层进行了对比研究.结果表明,所设计的铁基合金熔覆层成形良好,基体组织由Fe-Cr固溶体相与γ-Fe相构成,其间包裹着大量弥散分布的富钼硼化物和M₂₃(B,C)₆硬质相,对熔覆层组织能够起到有效的支撑和强化作用.铁基熔覆层的宏观硬度平均值高达64.2HRC,其相对耐磨性明显优于NiCrBSi+25%WC熔覆层,并达到NiCrBSi熔覆层的8倍以上.     

填粉率对复合粉粒和实心焊丝堆焊合金组织及耐磨性的影响

粉末组分经干混、掺粘结剂湿混、旋转造粒、烧结和筛分等工序制备成10目 ~ 30目的复合粉粒，将之预置于焊道，以H08A实心焊丝为电弧载体，自保护明弧堆焊高铬合金. 借助光学显微镜、X射线衍射仪、扫描电镜等方法，研究了填粉率对复合粉粒和实心焊丝堆焊合金组织及耐磨性的影响. 结果表明，随着填粉率由30%提高至45%，该堆焊合金的显微组织由亚共晶转变为过共晶结构，主要基体由γ-Fe转变为α-Fe，M₇C₃相形态由沿晶断续网状或树枝状转变为颗粒状或块状. 磨损试验结果表明，该方法堆焊的高铬合金耐磨性优良，与药芯焊丝堆焊高铬合金相当，制备工艺更为简便且经济，合金磨损机制包括磨粒的微切削和显微剥落两种形式.     

等离子熔覆Fe基/WC-10Co-4Cr涂层的组织与性能研究

目的 制备高强度和高硬度的耐磨性涂层,用于已磨损的机械零件表面,以延长其使用寿命,避免机器因磨损而带来的各种故障。方法 采用等离子熔覆技术在40CrMnMo表面制备WC-10Co-4Cr/Fe300合金复合熔覆层,研究不同质量分数WC-10Co-4Cr对熔覆层组织和性能的影响。利用金相显微镜、超景深光学显微镜、SEM、EDS、XRD对熔覆层的组织形貌进行表征和物相分析,借助数显显微硬度计和销盘式摩擦磨损试验机测试熔覆层的硬度和耐磨性。结果 WC-10Co-4Cr/Fe300合金作为一种复合材料,与基材形成了冶金结合,结合区域无孔洞和裂纹。熔覆层微观结构随着WC-10Co-4Cr含量的增加,逐渐由柱状晶向树枝晶过渡,它主要由Fe₆W₆C、(Cr、Fe)₂₃C₆和WC相组成。熔覆层的平均硬度大致随着WC-10Co-4Cr含量的增加而提高,当WC-10Co-4Cr的质量分数达到20%时,熔覆层的硬度最高(518.5HV0.2),大约是基体硬度的1.7倍。熔覆层的主要摩擦机理为磨粒磨损,随着WC-10Co-...     

A comparative study of the structure and wear resistance of NiCrBSi/50 wt.% WC composite coatings by laser cladding and laser induction hybrid cladding

NiCrBSi/50 wt.% WC composite coatings were produced on carbon steel via laser cladding (LC) and laser induction hybrid cladding (LIHC). The microstructure and phase constituents of the composite coatings before dry sliding wear and the wear behavior were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Under the same laser processing parameters, the cladding height during LC was much higher than that during LIHC, whereas the dilution, cladding width, heat-affected-zone (HAZ) and efficiency of powder utilization during LC were much smaller than those during LIHC. Additionally, WC particles suffered from more severe heat damage during LIHC compared with those during LC, resulting in the precipitation of herringbone, dendritic and blocky carbides and inhomogeneous distribution of WC particles in the composite coating. However, the increase of the laser scanning speed during LIHC decreased the heat damage of WC particles, improved the homogenous distribution of WC particles and further increased the microhardness of the binder metal, which in turn led to an increase in the wear resistance of the composite coating.     

激光熔覆Ni—WC金属陶瓷层的耐磨性分析

本文以单晶碳化钨铸造碳化钨和烧结碳化钨颗粒为陶瓷相，镍基自熔合金为粘结金属，研究了不同种类，粒度和含量的碳化钨颗粒对激光熔覆金属陶瓷层的磨粒磨损性能的影响。结果表明碳化钨颗粒的种类粒度与含量对金属陶瓷激光熔覆层的耐磨性能影响明显，熔覆层耐磨性能随碳化钨含量的变化趋势取决于碳化钨颗粒的种类。     

微米WC增强Ni60合金高频感应熔覆涂层耐磨性能

采用高频感应熔覆方法在Q235低碳钢基体上制备了不同含量的微米WC增强Ni60A合金复合涂层.用MLS-225型湿砂橡胶轮磨粒磨损试验机评价了涂层的耐磨性能,利用SEM,XRD观察并分析了涂层的显微组织和磨损表面形貌.结果表明,在相同试验条件下,涂层的硬度和耐磨性随WC含量的增加而提高,当WC含量少于30%时,WC分布不均匀,主要集中于涂层的中部,涂层中Cr7C3相以粗大的六方状和长条状存在,不利于涂层耐磨性的提高;当WC含量达到50%时,Ni基合金中加入WC的含量达到了合适比例,耐磨性最佳,相对耐磨性为Ni60A涂层的6.5倍;当WC含量达到60%时,涂层的硬度最高,但出现了较多的孔洞,大量未熔的WC颗粒在磨粒的反复作用下剥落形成了大的剥落坑,导致耐磨性下降.涂层与基体实现了冶金结合,涂层的磨损机制主要为轻微的塑性切削和硬质相的脆性剥落.     

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.