多道搭接激光熔覆NiCrBSi合金层组织及性能

为了改善40Cr钢的表面状态,拓展其应用范围,采用CO2激光器及LASERCELL-1005六轴六联动三维激光加工机床在40Cr钢表面多道搭接激光熔覆了NiCrBSi合金粉末,利用扫描电镜、金相显微镜、磨损试验机、盐雾试验机等对熔覆层的组织及性能进行了研究.结果表明:激光熔覆层由熔覆区、结合区和热影响区3部分组成.多道...     

激光重熔对NiCrBSi等离子喷涂层显微结构和性能的影响

1Crl8Ni9Ti不锈钢表面的NiCrBSi等离子喷涂层存在孔洞及与基体结合差等缺陷,为此进行了激光重熔处理.采用扫描电镜和显微硬度压痕仪分别对涂层的显微结构和力学性能进行了对比研究,采用SRV试验机评价了涂层激光重熔前后的滑动摩擦磨损性能,研究了激光重熔对NiCrBSi等离子喷涂层结构和性能的影响.结果表明:经过激...     

Effect of Nb addition on microstructure and properties of laser cladding NiCrBSi coatings

NiCrBSi coatings with different Nb additions have been prepared by laser cladding. The microstructure, phase composition, hardness, and wear resistance of the coatings were studied by scanning electron microscopy (SEM), electron probe microanalyser (EPMA), X-ray diffraction (XRD), microhardness tester and M-200 wear tester. The results show that the phases in the NiCrBSi coating without Nb addition include γ-Ni, Cr₂₃C₆, Cr₇C₃, Ni₃B, Ni₃Si₂ and CrB. The NbC phase appears in coatings after the addition of Nb element. When the addition of Nb is 2?wt-%, the NbC particles with a size of about 1.2?μm were found in the coating, and the amount of NbC is about 1.8?vol.-%. With the increase of Nb addition, the size and amount of NbC in the coatings also increased. When the addition of Nb is 6?wt-%, the size of NbC is about 2.3–6.1?μm and the morphology of NbC changed from particle to quadrangular and petaloid shaped. In addition, when the addition of Nb is 2?wt-%, the hardness and wear resistance of the coating are the best, and the wear resistance of the coating is 104% higher than that without Nb addition.     

WC/W_2C_P在NiCrBSi合金中的分解机理及其表面渗碳改性

为了抑制铸造碳化钨颗粒(WC/W2C P)在复合材料制备过程中的过度分解,利用SEM、EDS和XRD等测试手段对WC/W2C P在Ni Cr BSi合金中的分解机理及其表面改性渗碳处理进行了研究。结果表明,铸造碳化钨由WC和W2C两相组成,在Ni Cr BSi合金中WC相比W2C相具有更好的化学稳定性。在熔烧法制备WC/W2C P增强Ni Cr BSi基复合材料涂层的过程中,基体熔液和WC/W2C P发生元素互扩散;WC/W2C P中的化学稳定性差的W2C相与从基体熔液中扩散过来的Ni、Cr等元素反应生成了富W、Ni的碳化物,而化学稳定性好的WC相几乎完整的保留下来;基体中的Ni、Cr元素与从WC/W2C P中扩散过来的W、C元素形成了富W、Ni、Cr的碳化物在凝固过程中析出。经渗碳表面改性后,WC/W2C P表面形成了化学稳定性好的WC壳层,该壳层能有效抑制WC/W2C P在基体中的扩散分解,减少基体中碳化物的析出。     

Tribological behavior and mechanism of NiCrBSi–Y2O3 composite coatings

The NiCrBSi–Y₂O₃ composite coatings were prepared on the surface of 45 carbon steel by plasma spray, the microstructure and tribological properties of the coatings were investigated. The results show that the NiCrBSi–Y₂O₃ composite coatings are mainly composed of γ-Ni, CrB, Cr₇C₃ and Y₂O₃. With addition of Y₂O₃, hard phases such as CrB, Cr₇C₃ emerge in composite coating, and the density of the composite coatings also increases. The NiCrBSi–0.5Y₂O₃ composite coating presents excellent tribological properties. Its friction coefficient is 0.175, which is about 37% of that of the pure NiCrBSi coating. The mass wear loss is 1.2 mg, which is reduced by 43% compared with the pure NiCrBSi coating. When the loads are 6–10 N, the NiCrBSi–0.5Y₂O₃ composite coating suffers from slight wear and the wear mechanisms are mainly adhesive wear accompany with slight micro-cutting wear and micro-fracture wear. As the load increases to 12 N, the wear mechanisms are adhesive wear and severe micro-cutting wear.     

Dry sliding wear behavior and corrosion resistance of NiCrBSi coating deposited by activated combustion-high velocity air fuel spray process

NiCrBSi is a Ni-based superalloy widely used to obtain high wear and corrosion resistant coatings. This Ni-based alloy coating has been deposited onto 0Cr13Ni5Mo stainless steel using the AC-HVAF technique. The structure and morphologies of the Ni-based coatings were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The wear resistance and corrosion resistance were studied. The tribological behaviors were evaluated using a HT-600 wear test rig. The wear resistance of the Ni-based coating was shown to be higher than that of the 0Cr13Ni5Mo stainless steel because Fe₃B, with high hardness, was distributed in the coating so the dispersion strengthening in the Ni-based coating was obvious and this increased the wear resistance of the Ni-based coating in a dry sliding wear test. Under the same conditions, the worn volume of 0Cr13Ni5Mo stainless steel was 4.1 times greater than that of the Ni-based coating. The wear mechanism is mainly fatigue wear. A series of the electrochemical tests was carried out in a 3.5 wt.% NaCl solution in order to examine the corrosion behavior. The mechanisms for corrosion resistance are discussed.     

Mo元素对NiCrBSi合金激光熔覆层开裂敏感性的影响

采用CO2固体激光器,在45CrNi钢表面制备了添加成分(质量分数,%)为0,2.5,5.0,7.5,10.0 Mo的NiCrBSi合金熔覆层,研究了Mo元素对熔覆层开裂敏感性的影响,并从线膨胀系数和熔覆层凝固组织特性两方面对其影响进行了分析.结果表明,NiCrBSi合金对裂纹很敏感,熔覆层表面出现大量横向宏观裂纹,NiCrBSi合金中添加质量分数5.0% Mo,可改善凝固组织中硬质相的成分和形态,降低熔覆层的线膨胀系数,二者综合作用,降低了熔覆层的开裂敏感性.     

WC-12Ni/NiCrBSi爆炸喷涂涂层制备及其滑动磨损特性

利用爆炸喷涂方法制备了不同比例的WC-12Ni/NiCrBSi涂层,研究了NiCrBSi含量对涂层的组织形貌、硬度与结合强度的影响,用扫描电镜和能谱仪分析了涂层的滑动磨损行为.结果表明:由于NiCrBSi的加入,改善了WC颗粒的熔融状态,提高了涂层的结合力,涂层中含15%的NiCrBSi时,可以明显的提高涂层的磨损抗力.     

铝合金表面激光熔覆NiCrBSi的空泡腐蚀性能

采用连续波2kW YAG激光器在6061铝合金表面激光熔覆NiCrBSi合金，利用扫描电子显微镜（SEM／EDX），X射线衍射仪等分析检测设备研究熔覆层的组织形貌，化学成分及相组成，利用超超波感应空泡腐蚀设备对熔覆层在3．5％NaCl水溶液中的空泡腐蚀性能进行了系统评价，从而总结出激光熔覆层及基材的空泡腐蚀机制。     

腐蚀介质条件下NiCrBSi/WC喷熔层的摩擦学性能研究

采用氧-乙炔火焰喷熔工艺,制备了碳化钨颗粒增强镍基合金喷熔层(NiCrBSi/WC),研究了它在腐蚀介质条件下的摩擦磨损行为与机理,并考察了载荷、滑动速度对其摩擦磨损性能的影响规律。研究结果表明:NiCrBSi/WC具有良好的耐腐蚀磨损性能,且当WC含量为20%时,腐蚀磨损率最低;WC含量超过20%后,由于喷熔层存在“腐蚀原电池”效应,其腐蚀磨损率增大。NiCrBSi/WC的腐蚀磨损率随载荷增加而变大,随速度增大而减小。载荷的增加使喷熔层的犁削磨损加剧,导致摩擦系数和磨损率增大;速度的增大造成摩擦界面温度上升,可生成摩擦转移膜,从而降低了喷熔层的磨损率。