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.     

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。     

WC增强镍基复合喷焊层的组织与磨粒磨损性能研究

采用扫描电镜、电子探针、X射线衍射和透射电镜技术分析了氧乙炔火焰喷焊WC增强镍基自熔性合金复合涂层的组织结构,并采用湿砂橡胶轮式磨粒磨损试验机对该涂层与等离子喷涂NiCr/Cr3C2涂层的磨损性能进行了实验比较.结果表明,复合喷焊层内形成了γ-Ni固溶体基体,其中弥散分布着大量细小的碳化物硬质相Cr3C2、B4C、Cr7C3、Cr23C6等.WC颗粒仅在边缘处发生部分溶解,与涂层基体形成了冶金结合,周围生成针状的碳化铬枝晶.该组织决定了喷焊层基体具有较高的硬度,WC增强颗粒与基体之间具有很高的结合强度.复合喷焊层具有很好的耐磨粒磨损性能,其磨损失重量仅为NiCr/Cr3C2涂层的57%.     

氧燃比对爆炸喷涂WC-17Co涂层组织和性能的影响

选用WC-17Co喷涂粉末,采用爆炸喷涂工艺,通过改变乙炔和氧气流量等喷涂参数在316L钢基体上制备了4种WC/Co涂层.采用X衍射仪、扫描电镜对对涂层的相结构和微观组织进行了研究;采用灰度法测试了涂层的气孔率;采用拉伸法测试了涂层的结合强度;采用小负荷维氏硬度计测试了开裂韧性;最后采用湿砂橡胶轮磨粒磨损试验机对各涂层磨粒磨损行为进行了研究.结果显示:随着氧燃比的增加,涂层中的WC分解程度增加,涂层的硬度增加,韧性、气孔率和抗磨粒磨损性能都是先增加后降低.氧燃比为1.5时,涂层具有最优的综合力学性能.     

不同喷涂距离WC10Co4Cr涂层抗磨损性能研究

采用超音速火焰喷涂技术制备出WC10Co4Cr涂层。利用显微硬度试验机测试了涂层的硬度,通过橡胶轮磨粒磨损试验和扫描电镜(SEM)对涂层磨粒磨损性能和磨损形貌进行分析,利用静态液压万能试验机进行涂层剥离测试分析。结果表明:涂层的硬度随着喷涂距离的增大而增加。WC10Co4Cr涂层,其磨损失效形式主要以小颗粒脱落为主。     

Ni基合金高速火焰喷焊层组织及耐磨性研究

使用QT-E-7/h型喷枪的高速火焰喷焊设备,在45圆钢表面喷焊添加了不同含量Ni包WC的Ni基合金粉末,并对喷焊层的微观组织、显微硬度及摩擦磨损性能进行研究。研究结果表明:喷焊层微观组织为奥氏体的基体上弥散分布着Fe Ni3,Cr2Ni3,Cr3Si,WC等相;Ni包WC含量在0%~30%范围内时,随着Ni包WC含量的增加,喷焊层显微硬度增加,耐磨性增强;当Ni基合金粉末中Ni包WC含量为27%时,喷焊层表层的显微硬度最高,耐磨性最好,耐磨性较不加Ni包WC提高了约1倍;喷焊层磨损机理以黏着磨损和磨粒磨损为主;当进一步增加Ni包WC含量达到30%时,喷焊层出现宏观裂纹,致使喷焊层无法成形。     

铁基合金等离子弧喷焊层组织及耐磨性研究

使用PT-40002ST型等离子弧喷焊设备,在45钢表面制备含有不同含量WC颗粒的铁基合金粉末喷焊层,并分别对喷焊层进行显微组织观察、显微硬度测试及摩擦磨损试验。研究结果表明:随着WC含量的增加,第二相增多;喷焊层的平均显微硬度较45钢的提高约2.5倍,且喷焊层表层硬度先提高后降低;当铁基合金粉末中w(WC)为10%时,喷焊层表层的显微硬度值最高,且耐磨性最好,耐磨性较不加WC时提高了约1倍,磨损机理以黏着磨损和磨粒磨损为主。     

高焓等离子喷涂WC-10Co4Cr涂层的耐磨性

为提高马氏体不锈钢（0Cr13Ni4Mo）的表面硬度及耐磨性能,对不锈钢表面进行高焓等离子喷涂WC10Co4Cr强化,对涂层进行组织观察和物相组成分析,并在不同温度下进行了摩擦磨损试验。研究表明：WC10Co4Cr涂层组织致密,主要由WC物相构成,另外还有少量的W2C和Co25Cr25W8C2。在室温和高温（400 ℃）时,WC10Co4Cr涂层均具有较低的摩擦因数。室温时,基体的磨损机制主要以粘着磨损和磨粒磨损为主。WC10Co4Cr涂层其磨损机制主要以微切削为主。400 ℃条件下,不锈钢基体的磨损机理主要以粘着磨损和剥层为主,磨痕边缘部位主要以磨粒磨损为主。WC10Co4Cr涂层试样的磨损机制主要以磨粒磨损为主,伴随有剥层现象出现。     

AC-HVAF制备WC-10Co-4Cr涂层抗磨粒磨损性能研究

采用活性燃烧高速燃气(AC-HVAF)喷涂工艺制备了WC-10Co-4Cr涂层,测试了涂层的结合强度、显微硬度、气孔率以及抗磨粒磨损性能。并利用XRD对喷涂粉末及涂层进行了相结构分析,用扫描电子显微镜对喷涂粉末、磨粒磨损后的涂层表面形貌进行了观察。结果表明:在喷涂过程中,仅有很少量的WC发生合金化。涂层的结合强度和显微硬度高,组织结构致密。在相同的实验条件下,16Mn钢的磨粒磨损质量损失是WC-10Co-4Cr涂层的266倍,这表明HVAF制备的WC-10Co-4Cr涂层具有优异的抗磨粒磨损性能。     

一种Fe-Cr-Si-B系合金喷焊层组织及性能

针对抽油泵、水煤浆泵等产品在工作过程中常见的腐蚀+磨粒磨损问题,采用雾化法研制了一种FeCr-Si-B系合金粉末。采用等离子弧喷焊方法分别制备喷焊耐磨层,并对合金粉末喷焊耐磨层进行渗透探伤以及化学成分、显微组织、硬度、耐磨性分析。结果表明,合金粉末的喷焊显微组织均由Cr3Si硬质相和A2基体韧性相组成,晶粒细小,抗裂性能优越,硬度值为58.1HRC;耐磨性为0.428 mg/100S,与Fe-36Cr-5C过共晶合金喷焊层耐磨性相当。该Fe-Cr-B-Si系合金粉末适合于腐蚀环境下低应力磨粒磨损工况的表面强化。     

Binder jet printed WC infiltrated with pre-made melt of WC and Co

WC-Co was made via binder jet additive manufacturing of tungsten carbide followed by melt infiltration with a Co-WC infiltrant. The goal of the study was to achieve fully densified parts in near-net shape with minimal shrinkage while keeping the Co content low. The exact amount of infiltrant was determined in order to fully densify with minimum shrinkage based on the actual volume taken up by WC powder in the preform based on theoretical density, the bounding volume of prints after shrinkage, and the volume from the infiltrant. The eutectic nature of the infiltrant enabled melting at much lower temperature compared to the melting temperature of pure Co. The density, microstructure, grain size, hardness, and fracture toughness were characterized. The shrinkage and net shaping were assessed with light scans. A detailed look at the fracture mechanics was assessed. This approach achieved highly dense WC-Co parts in net-shape with Co vol% of near 29 (Co wt% ~19), density of 96.2% theoretical, hardness of 8.34 GPa, grain size of 7.7 μm, magnetic saturation of 0.5 T, room temperature thermal conductivity of 125 W/mK, and fracture toughness of 24.7 MPa·m^1/2.     

碳化钨含量对钴基碳化钨复合喷熔层耐磨性的影响

为提高20钢的耐磨料磨损性能,利用氧一乙炔火焰喷涂的方法制备了不同WC含量的钴基WC复合喷熔层。显微组织分析表明,复合喷熔层与基体结合良好,喷熔层内WC颗粒分布均匀。磨损试验结果表明,钴基WC复合喷熔层具有优异的耐磨性能,随WC含量的增加,喷熔层耐磨性能增强。     

Phase transformation of NiCrBSi–WC and NiBSi–WC arc sprayed coatings

The coating microstructures of electric arc sprayed NiCrBSi–WC and NiBSi–WC coatings were investigated. It was found that, for NiCrBSi–WC coating, the resulting microstructure consists of NiCr, NiCrW solid solutions and WC/W₂C as major phases. For NiBSi–WC coating, the major phases are Ni, NiW solid solution and WC/W₂C. Some B is present within the coatings as inclusions. The amount of WC/W₂C was reduced in both coatings due to the formation of the NiCrW and NiW solid solutions containing a large amount of W. Precipitation of W-rich phase from NiCrW and NiW solutions was also observed but the transformation is restricted by the fast cooling rate characteristic of the spraying process. There is more dissolution of WC/W₂C into the matrix in NiBSi–WC coating resulting in a greater reduction in the microhardness of this coating. Wear test results, however, show that even though the NiBSi–WC coating possesses lower microhardness, it is more effective against dry sliding wear than the NiCrBSi–WC coating, owing to better metallurgical bonding between the matrix and the carbide as a result of WC/W₂C dissolution.     

WC/Ni和WC/Cu基复合覆层的耐气蚀性能

分别在NiCrSiB和CuNiSiB自熔合金粉末中添加WC颗粒 ,利用氧乙炔焰粉末喷焊工艺制备覆层。用超声波振动气蚀仪研究覆层的耐气蚀性能 ,用扫描电镜观察覆层表面气蚀破坏形貌。结果表明 :复合覆层的耐气蚀能力比基体材料强。探讨了覆层的气蚀破坏机理。     

WC粒度对WC/10Co注射成形工艺的影响

研究了不同粒度的WC粉末对WC/10Co注射成形工艺(PIM)的影响,分析了WC粒度对喂料流变性、注射坯质量、脱脂工艺和烧结工艺的影响机理。结果表明:WC粒度越小,WC/10Co喂料流变性越差,注射坯质量越低,溶剂脱脂速率越高,合金形状偏差越大。超细WC/10Co喂料存在粉末团聚颗粒、粘结剂包裹不充分,其热稳定性低、流动性降低56%,注射坯致密度下降5%;超细WC-10Co合金的线收缩率达到20.80%,尺寸偏差为2.85%,脱脂-真空烧结时易出现脱碳现象。     

WC块球磨工艺对WC粉及其合金性能的影响

本文在球料比为1.5∶1的情况下对40型和200型WC块进行球磨,研究了球磨时间对球磨后WC粉的化学成分、粒度及粒度分布、亚晶尺寸、形貌等的影响.然后,选取球磨1h和16 h的WC粉为原料,在相同的工艺条件下制备成合金,观察了合金形貌,检测了合金磁力、密度、硬度等性能.结果表明:随着球磨时间的延长,WC粉的粒度和总碳量降低,氧含量增加,粒度分布发生明显变化:随着球磨时间的延长,粒度分布曲线的峰值不断向左(即粒度细的方向)快速移动;随着球磨时间的延长,首先是粘结的WC颗粒分离,然后多晶WC颗粒沿晶界面破裂,最后不规则的粗大WC晶粒发生穿晶断裂并产生大量的微细粉末;随着球磨时间的延长,晶粒内部的亚晶尺寸不断变小.40型WC块经过长时间球磨后,其制备的合金的矫顽磁力和抗弯强度都减少,而其它性能没有明显变化.200型WC块经过长时间球磨后,其制备的合金的矫顽磁力减少,而其它性能也没有明显变化.200型WC块长的球磨时间容易造成合金中WC晶粒不均匀长大.     

WC硬质合金复合轧辊的加工

介绍了加工WC硬质合金轧辊时刀具、轧辊轧槽和月牙横肋加工工艺的选择方法;对超硬材料刀具常见磨损形式及其产生原因进行了分析,并提出了预防措施。     

WC溶解对WCp/钢基表层复合材料组织和性能的影响

利用V-EPC法制备了WC颗粒增强钢基表层复合材料.通过金相、扫描电镜、XRD、显微硬度及冲击磨料磨损性能测试等手段重点研究了在预制层中添加镍基自熔合金粉末(Ni6025 WC)后,WC在基体中的溶解对复合材料组织和性能的影响.结果表明,WC在复合层中全]溶解使复合层基体中出现珠光体,残留奥氏体,马氏体以及M6C型碳化物,经分析知该M6C型碳化物为Fe3W3C.本试验得到的试样显微硬度与同类WC/钢基表层复合材料相比显著降低,冲击磨料磨损下的体积磨损率也较高.这些均表明WC在基体中过度溶解和Fe3W3C在基体中的含量较多时,复合材料的性能较差.     

Morphology of WC grains in WC–Co alloys: Theoretical determination of grain shape

A theoretical approach to predict grain morphology from interface energies computed using density-functional theory is presented and applied to the WC–Co system. The dependences of the WC grain shape on the geometrical misfit at the Co/WC metal–ceramic interface, and on the carbon chemical potential are investigated. The WC grains are predicted to be hexagonal when the interfaces are assumed to be coherent, and change to a truncated triangular shape where the long prism side lengths are five times longer than the short side lengths, when the interfaces are assumed to be incoherent.     

Properties of WC–8Co hardmetals with plate-like WC grains prepared by plasma-assisted milling

WC-8C0 hardmetals with different proportions of prismatic WC grains and plate-like WC grains were directly produced through sintering the W-C-8C0 elemental powder mixture which was fabricated by dielectric barrier discharge plasma(DBDP)-assisted milling.The morphology of prepared WC-8C0 hardmetals,geometry and the preferential orientation of plate-like WC were investigated by X-ray diffraction(XRD) and scanning electron microscopy(SEM) analysis.The results demonstrate that the microstructure and mechanical properties of the sintered hardmetals are related to the morphology of W grain which is dependent on DBDP-milling time.The DBDP for 1 h(DBDP-1 h)-milled W-C-Co powder contains granular W particles that tend to form prismatic WC grains,while the DBDP for 3 h(DBDP-3 h)-milled powder contains lamellar W particles that generate plate-like WC grains.By adjusting the weight ratio of DBDP-1 h powder and DBDP-3 h powder in W-C-8C0 mixture,the proportion of plate-like WC in the hardmetals can be controlled,and relatively high transverse rupture strength(TRS) is obtained as the proportion of plate-like WC grain in the hardmetals is about 35%in present experimental condition.