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Cr3C2-NiCr涂层是中高温下理想的耐磨、抗氧化、耐蚀涂层,常用于高温下的燃气冲蚀磨损、磨粒磨损、微动磨损、硬表面磨损等场合.文中采用超音速等离子喷涂的方法在CuCrZr合金表面制备Cr3C2-NiCr涂层,并采用超声冲击的方法对涂层进行后处理.结果表明,经超声冲击处理后,涂层孔隙率由2.34%降低至1.83%;涂层的平均显微硬度由8.9 GPa提高至9.6 GPa,且硬度分布更均匀;在650℃下进行热震试验,涂层的热震寿命显著提高,热震裂纹的扩展路径也发生了变化. 相似文献
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利用等离子弧喷涂技术在结晶器CuNiCoBe基体上制备了Cr3C2-NiCr涂层,采用正交试验法研究了喷涂工艺参数对涂层与基体结合强度的影响,对拉伸断面的形貌和涂层的显微结构进行了观察和分析.结果表明,影响Cr3C2-NiCr涂层与CuNiCoBe基体结合强度的主次因素依次为:送粉速率>主气流量>喷涂距离>喷涂功率;经正交试验优化后的喷涂工艺参数为:喷涂距离90mm,主气流量56.6L/min,送粉速率20 g/min,喷涂功率25 kW;优化后,涂层与基体的结合强度可达18.5 MPa;涂层截面的显微硬度分布符合正态分布. 相似文献
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采用超音速火焰喷涂(high-velocity oxygen-fuel, HVOF)技术,在1Cr18Ni9Ti不锈钢表面制备Cr3C2-NiCr金属陶瓷复合涂层. 研究了涂层的显微组织、相组成以及涂层和不锈钢的冲蚀行为和机理,探讨了冲蚀角与耐冲蚀性能的关系规律. 结果表明,涂层组织结构致密均匀,主要由Cr3C2以及少量的Cr7C3, Cr23C6和(Ni, Cr)固溶体相组成. Cr3C2-NiCr涂层的耐冲蚀性能随着冲蚀角的增大而减小,在低冲蚀角下涂层的破坏形式主要为微切削,重量损失较低,表现出优异的耐冲蚀性能. 随着冲蚀角的增大,冲蚀沙粒对涂层产生垂直冲击作用,粘结相与硬质相之间产生裂纹导致粘结相脱落,硬质相失去粘结相的支撑作用而裸露出来,在冲蚀沙粒的持续攻击下剥落,形成许多小冲蚀坑. 随着剥落硬质相数量的增加,小冲蚀坑逐步发展为大冲蚀坑,重量损失较大,耐冲蚀性能较差. 相似文献
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采用等离子喷涂技术在铬锆铜(CrZrCu)基体表面制备了Cr3C2 p/NiCr涂层。利用X射线衍射仪(XRD)、扫描电镜(SEM)等仪器研究了涂层的显微组织及结构,采用磨粒磨损试验机对Cr3C2 p/NiCr涂层与电镀NiCo层的磨损性能进行了测试比较。结果表明:涂层组织呈片层状结构,在NiCr合金片层上分布着未熔的Cr3C2和Cr7C3、Cr2Ni3、CrNi析出相。与电镀Ni-Co镀层相比,Cr3C2 p/NiCr涂层具有较高的硬度和耐磨粒磨损性能,其磨损量仅为电镀层的35%。 相似文献
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分别用亚音速和超音速等离子喷涂方法在CuCrZr合金表面制备了NiAl涂层,通过正交试验对工艺参数进行优化,测定了涂层与基体的结合强度。利用SEM、EDS、XRD等设备研究了涂层的组织结构、物相变化及涂层与基体间的结合方式。结果表明,超音速等离子喷涂制备的NiAl涂层粒子变形充分、组织致密,涂层与基体间的结合强度明显高于亚音速喷涂层;两种方法制备的涂层与基体的界面处均主要为Al,界面的局部区域Cu-Al发生反应生成了Cu3Al2、CuAl2、CuAl等新相,形成了1~3 µm宽的“微冶金结合”层。 相似文献
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选用等离子喷涂技术在CuCo2Be合金表面制备Cr3C2-NiCr/NiAl复合涂层。选用DTA、XRD、SEM、EDS等分析手段探讨Cr3C2-NiCr/NiAl复合涂层的形成机理及其组成涂层的化合物、物相的形成特点及规律。结果表明:DTA分析发现镍铝打底层在热喷涂过程中由于系放热反应,可能生成Ni2Al3、NiAl3、NiAl等物相;SEM、EDS分析发现复合涂层组织呈现明显的层状,在镍铝打底层中镍铝化合物为角状;XRD分析发现涂层物相在成形的不同阶段和时间内其生成的化合物类型、数量都呈现不同的变化。利用XRD、EDS分析界面处各相的生成及元素的分布、扩散情况,表明在界面处存在一定的元素扩散,界面为微冶金结合。 相似文献
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采用高速电弧喷涂技术在Q235钢表面制备了FeMnCrNi/Cr3C2涂层。通过正交试验研究了喷涂电压、喷涂电流和喷涂距离对涂层形貌及性能的影响,获得了涂层制备的最佳工艺参数。利用扫描电镜、X射线衍射仪、能谱仪、显微硬度仪与激光共聚焦显微镜等研究了最佳工艺参数下制备的FeMnCrNi/Cr3C2涂层的形貌及性能。结果表明:影响涂层性能的主次因素顺序为:喷涂距离、喷涂电压、喷涂电流。最佳工艺参数为:喷涂电压31 V、喷涂电流240 A、喷涂距离200 mm。采用最佳工艺参数制备的涂层孔隙率为1.99%,显微硬度为719 HV0.1,是Q235钢的3.5倍,涂层的平均磨痕宽度、深度和截面积分别为281.95μm、4.42μm和564.81μm2,相比Q235钢分别减小了60%、72%和89%,具有更优的耐磨性;涂层的主要磨损形式为磨粒磨损。 相似文献
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以团聚烧结和烧结包覆两种工艺制备的Cr3C2-25%NiCr粉末为原料,运用超音速火焰喷涂(HVOF)技术制备了Cr3C2-NiCr涂层,分析比较了两种涂层的显微组织、孔隙率和硬度,运用橡胶轮磨损试验机测定了涂层在不同磨损条件下的耐磨粒磨损性能,研究了粉末制备工艺和磨损工艺条件对涂层磨损质量损失的影响。结果表明,烧结包覆粉末所沉积的涂层具有高的致密度、硬度和良好的耐磨性,而团聚烧结粉末所形成的涂层耐磨粒磨损性能较差。磨损工艺条件对涂层的磨损质量损失有很大影响,在大载荷或粗磨粒作用的工况下,涂层的磨损质量损失最大。 相似文献
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Vacuum plasma spraying (VPS) was used to spray a Cr3C2-NiCr coating of ∼ 150, 300 and 450 μm in thickness onto a plain carbon steel substrate, employing a commercially available Cr20Ni9.5C powder. The splat microstructures observed in the coating were found to consist of a NiCr matrix with a predominant Cr3C2 phase, besides Cr7C3 and Cr2O3. The adhesion of the coating to the substrate was evaluated by means of interfacial indentation techniques. It has been found that the interfacial toughness value changes from 7.6 to 10.1 MPa m1/2 when the thickness increases from 150 to 450 μm. Also, it has been found that the parameter Kcao, determined by linear regression from the Kca versus 1 / e2 curve by means of the interfacial indentation model advanced by Chicot et al., has a value of ∼ 9.8 MPa m1/2. 相似文献
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M. Suarez M. Traisnel D. Chicot E.S. Puchi-Cabrera M.H. Staia 《Surface & coatings technology》2008,202(18):4566-4571
The objective of the present work is to determine the influence of the heat treatment on the corrosion resistance of a Cr3C2-NiCr coating of 450 μm thickness, deposited by a vacuum plasma spray process (VPS) on a steel substrate. The post-heat treatment of the as-deposited coating was carried out in Ar at 400 °C and 800 °C, respectively. The coatings were characterized by means of an electron probe micro analyzer (EPMA) with wavelength dispersive X-ray spectrometers (WDS). It was found that no significant changes were produced as a consequence of the heat treatment carried out at 400 °C. Therefore, the corrosion experiments were conducted for the substrate, the as-deposited coating and the post-heat treated coating at 800 °C. Potentiodynamic polarization showed that the annealed coating at 800 °C has a better corrosion resistance than the as-deposited coating. The corrosion current density (Icorr) of this coating was approximately 3 and 4 times smaller than that corresponding to the as-deposited coating and steel substrate, respectively. This significant improvement of the corrosion behavior of the post-heat treated coating is mainly due to both the microstructural changes that take place in the coating and the diffusion of Ni into Fe at the coating-substrate interface, which ensures the presence of a metallurgical bond. 相似文献
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In the present work the corrosion resistance of micro-cracked hard chromium and Cr3C2-NiCr (HVOF) coatings applied on a steel substrate have been compared using open-circuit potential (EOC) measurements, electrochemical impedance spectroscopy (EIS) and polarization curves. The coatings surfaces and cross-section were characterized before and after corrosion tests using optical microscopy (OM) and scanning electron microscopy (SEM). After 18 h of immersion, the open-circuit potential values were around −0.50 and −0.25 V/(Ag∣AgCl∣KClsat) for hard chromium and Cr3C2-NiCr, respectively. The surface analysis done after 12 h of immersion showed iron on the hard chromium surface inside/near surface cracks, while iron was not detected on the Cr3C2-NiCr surface even after 18 h. For longer immersion time hard chromium was more degraded than thermal sprayed coating. For hard chromium coating a total resistance values between 50 and 80 kΩ cm2 were measured and two well-defined time constants were observed, without significant change with the immersion time. For Cr3C2-NiCr coating the total impedance diminished from around 750 to 25 kΩ cm2 as the immersion time increased from 17 up to 132 h and two overlapped time constants were also observed. Polarization curves recorded after 18 h of immersion showed a lower current and higher corrosion potential for Cr3C2-NiCr coating than other samples studied. 相似文献
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文中用等离子喷涂在CuCo2Be表面制备了Cr3C2-NiCr涂层,并分别在500,550,600,650℃进行热震试验,研究温度对其疲劳寿命的影响;选用XRD,SEM,EDS等研究了涂层及化合物相的形成、不同温度热震后涂层内、外表面的微观形貌、氧化产物等.结果表明,涂层呈现层状,化合物为角状Cr3C2-NiCr,涂层与界面的结合以机械结合为主;XRD分析发现涂层中形成了一定非晶相,热震后涂层中存在铜、镍氧化物.分析其热震失效机制为:500℃时主要是热膨胀系数突变引起的应力与氧化共同作用;随热震温度升高,涂层与基体结合处应力增大,涂层失效机制逐步转变为应力主导失效. 相似文献
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Lingzhong Du Chuanbing HuangWeigang Zhang Tiegang LiWei Liu 《Surface & coatings technology》2011,205(12):3722-3728
NiCr clad hexagonal BN powder (NiCr/hBN) was added to NiCr/Cr3C2 feedstock to improve the tribological properties of chromium carbide nichrome coating. The microstructure, flowability and apparent density of the composite powder, as well as the structure and mechanical properties of the plasma sprayed coating were characterized. The friction and wear behavior of the NiCr/Cr3C2-NiCr/hBN coating from ambient temperature up to 800 °C was evaluated on a ball-on-disk wear tester and compared with that of NiCr/Cr3C2 coating and NiCr/Cr3C2-NiCr/BaF2·CaF2 coating. The results show that NiCr cladding can reduce the decarburization of Cr3C2 and oxidation of hBN during the thermal spray. The main wear mechanisms of the NiCr/Cr3C2-NiCr/hBN composite coating are ploughing and adhesive wear. Layered hexagonal BN particle reduce the direct contact and severe adhesion between friction pairs, thus decreasing the friction coefficient. The NiCr/Cr3C2-NiCr/hBN composite coating shows a promising application in the high temperature environment with the request of both wear resistance and friction reduction. 相似文献
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Gang-Chang Ji Chang-Jiu Li Yu-Yue Wang Wen-Ya Li 《Surface & coatings technology》2006,200(24):6749-6757
Cr3C2–NiCr coatings were deposited by high velocity oxy-fuel (HVOF) process with different spray parameters to examine dominant microstructural factors in abrasive wear of the coatings. The microstructure of the HVOF sprayed Cr3C2–NiCr coatings was characterized by scanning electron microscopy and transmission electron microscopy (TEM). The apparent average size and volume fraction of carbide particles in the coatings were estimated through a quantitative imaging analysis. The formation of carbide phases in the coating was discussed based on the TEM observation results. The abrasive wear behavior of the coating was evaluated by the dry rubber wheel abrasive wear test and the wear mechanisms were elucidated. Influences of apparent size and volume fraction of carbide particles on the abrasive wear weight loss were examined through correlating the proposed relation with the experimental results. Results showed that Cr3C2 particle size was significantly reduced after the spraying and Cr7C3 carbide was present around Cr3C2 particles, and Cr23C6 carbide was dispersed in NiCr alloy matrix with a nano-crystalline structure. The three carbides were formed in the coating through different mechanisms. The removal of carbide particles in the coating was mainly responsible for the abrasive wear of the coating. The content and particle size of the Cr3C2 carbides were the two key factors controlling the abrasive wear of the HVOF sprayed Cr3C2–NiCr coatings. 相似文献