电火花沉积制备Fe-8B-Mo非晶涂层的可行性

为研究Fe-8B-Mo合金的非晶形成能力,采用电火花沉积工艺制备了4种Fe-8B-x Mo(x=13.62,23.62,33.62和43.62,w/%)合金涂层。通过X射线衍射仪(XRD)表征涂层的物相组成,探索获得非晶涂层的可行性,并采用扫描电镜(SEM)、显微硬度测试及摩擦磨损试验进一步研究所得涂层的微观组织与性能。结果表明:4种涂层都由非晶相、马氏体相和Fe2B相组成,其中,13.62%Mo涂层主要含Fe2B相和马氏体相,而23.62%Mo、33.62%Mo和43.62%Mo涂层主要含非晶相,且随着Mo含量的增加,涂层中非晶相含量逐渐减少。4种涂层的组织结构致密,缺陷少,与基体呈良好的冶金结合。23.62%Mo涂层具有最大的峰值显微硬度(1 138.1 HV0.05);同时,该涂层在摩擦磨损的稳定阶段具有最小的平均摩擦因数,且其2 h的磨损质量也最小,表现出更好的摩擦磨损性能。4种涂层的磨损机制均为磨粒磨损和疲劳磨损。     

电火花沉积非晶涂层的组织结构与摩擦磨损性能

以Zr₅₅Al₁₀Ni₅Cu₃₀非晶态合金棒为电极,利用电火花沉积技术在ZL101铝合金表面制备了锆基合金涂层.利用X射线衍射仪（XRD）、扫描电镜（SEM）、显微硬度计和摩擦磨损实验机等对涂层的微观结构、表面形貌、显微硬度和摩擦磨损性能进行了分析测试.结果表明,沉积层表面较致密、均匀,为典型的“溅射状”花样形貌;沉积层主要由非晶、ZrO₂和Cu₈Zr₃等相组成;沉积层的平均显微硬度为1 555 HV 0.01,约为基材的15倍,摩擦系数仅为0.096,呈现出良好的减摩耐磨特性,沉积层的磨损机制主要为疲劳磨损和磨粒磨损.     

脉冲能量对电火花沉积Mo_2FeB_2基金属陶瓷涂层组织与性能的影响

为研究脉冲能量对电火花沉积制备Mo2Fe B2基金属陶瓷涂层组织及性能的影响,在3种脉冲能量(1.35,6.41和17.81 J)下分别制备了沉积涂层。采用扫描电镜(SEM)、X射线衍射仪(XRD)、电子探针(EPMA)、显微硬度计及摩擦磨损实验机对涂层的组织与性能进行研究和表征。结果表明:3种脉冲能量所制备的涂层物相组成均由非晶相、马氏体和Fe3B相组成,脉冲能量17.81 J时涂层的非晶相含量最低;单个沉积点的溅射范围和涂层表面裂纹数随着脉冲能量的增大而增大,涂层厚度随脉冲能量增加到一定厚度后变化不显著;涂层与基体间形成良好的冶金结合。脉冲能量6.41 J时,涂层截面具有最高的峰值显微硬度1 349 HV0.05;同时,该涂层稳定阶段的摩擦因数(0.313)和1 h磨损量(0.7 mg)均为3种涂层中最低,耐磨性最佳。     

TiN/MT-TiCN/Al2O3/ZrCN多层涂层的摩擦磨损性能

采用化学气相沉积(CVD)技术在硬质合金表面沉积TiN/MT-TiCN/Al2O3/ZrCN多层涂层,并对其进行微喷砂处理.采用扫描电镜(SEM)表征涂层的组织结构,利用显微硬度计、纳米压痕仪、划痕测试仪和往复式摩擦磨损实验机(UMT-3)测试涂层的硬度、结合强度和摩擦磨损性能,并与TiN/MT-TiCN/Al2O3/TiOCN涂层进行比较.结果 表明:TiN/MT-TiCN/Al2O3/ZrCN涂层的磨损机理主要包括磨粒磨损、粘着磨损、氧化磨损和疲劳磨损.相比于摩擦1h,TiN/MT-TiCN/Al2O3/ZrCN涂层摩擦2h,剥落增多,且磨粒磨损、粘着磨损和疲劳磨损加剧,磨损率增加了33.3％;摩擦3h,涂层磨粒磨损、粘着磨损和疲劳磨损进一步加剧,但剥落减轻,磨损率较摩擦2h略有降低.摩擦1h,TiN/MT-TiCN/Al2O3/ZrCN涂层的摩擦系数(0.33)比TiN/MT-TiCN/Al2O3/TiOCN涂层(0.39)低;尽管TiN/MT-TiCN/Al2O3/ZrCN涂层韧性好,疲劳磨损较轻,但磨粒磨损严重,且存在明显剥落,磨损率高,耐磨性较差.     

碳化铬基金属陶瓷电火花沉积涂层的微观组织与性能

采用电火花沉积分别制备了碳化铬基金属陶瓷单涂层和碳化铬基金属陶瓷/Ni复合涂层。采用X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计和摩擦磨损试验机对比研究了单涂层和复合涂层的物相、微观组织结构、显微硬度和摩擦磨损性能。结果表明,两种涂层组织结构致密,与基体呈良好的冶金结合,并在涂层内形成了纳米晶的微观组织。复合涂层中FeCr_0.29Ni_0.16C_0.06韧性相含量增加,在涂层界面处存在过渡层Ni,并以塑性变形的方式释放了更多沉积时产生的热应力,因而涂层裂纹明显减少。复合涂层的峰值硬度(1186HV_0.05)虽略低于单涂层,但该涂层具有最小的摩擦系数(0.2462),1h磨损量仅为单涂层的1/3,因此表现出更好的耐磨性能,其主要磨损机制为磨粒磨损和疲劳磨损。     

不同气氛下电火花沉积钛合金涂层的组织性能

分别在氮气、氩气和空气3种气氛下,在45钢上电火花沉积制备TC4钛合金涂层。利用OM、SEM、EDS、XRD、XPS等对钛合金沉积层的微观形貌、组织结构进行分析;利用纳米力学探针仪测试对比沉积层的力学性能;采用CETR摩擦磨损仪测试涂层的耐磨性。结果表明:氮气下电火花沉积生成含TiN及少量TiO和TiO2的陶瓷增强层。氮气中制取的涂层微裂纹较明显,但几无坑蚀和微孔,表面形貌优于氩气和空气下的沉积层。纳米硬度高达15.18GPa,无需增加沉积层厚度,即可获得较高硬度和抗变形能力。其摩擦因数为0.41,磨损量为2.2mg,均远低于45钢,也低于空气和氩气下制备的普通的钛合金涂层,并且改善了钛合金涂层的粘着磨损。     

轧辊表面电火花沉积涂层的耐磨性

采用电火花沉积工艺,用WC陶瓷硬质合金在铸钢轧辊表面制备了一层合金涂层。采用X射线衍射仪、扫描电镜、显微硬度计等对沉积层的相结构、显微组织、显微硬度及耐磨性能进行了分析。结果表明:沉积层主要由Co3W3C、Fe3W3C、W2C、Si2W等相组成;沉积层与基体呈冶金结合,细小的硬质相弥散分布于沉积层中;沉积层的平均硬度为1915 HV0.3,约是基体硬度(352 HV0.3)的5.4倍;其室温耐磨性能比基体提高了2.1倍,高温耐磨性能比基体提高了1.9倍。室温下沉积层的主要磨损机理为磨粒磨损;高温下沉积层的主要磨损机理为粘着磨损、氧化磨损和疲劳磨损。     

电火花沉积 Fe 基涂层的组织及耐磨性能

通过电火花沉积技术在P20模具钢表面制备了Fe基涂层,利用SEM,XRD及摩擦磨损试验机等分析了涂层的组织结构、显微硬度及耐磨性能。结果表明:电火花沉积Fe基涂层组织均匀、致密;涂层中靠近界面处的组织为柱状枝晶,而涂层中上部组织为超细晶粒。涂层的平均硬度为637.1HV0.1,相比基体提高了1倍;涂层耐磨性优于基体,涂层中弥散分布的Cr7C3,CrB及Fe3C等硬质是Fe基涂层硬度及耐磨性提高的主要原因。涂层的磨损机理主要为磨粒磨损的微切削和疲劳磨损。     

电火花沉积碳化铬基金属陶瓷涂层的微观组织与性能

采用电火花沉积分别制备了碳化铬基金属陶瓷单涂层和碳化铬基金属陶瓷/Ni复合涂层。采用X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计和摩擦磨损试验机对比研究了单涂层和复合涂层的物相、微观组织结构、显微硬度和摩擦磨损性能。结果表明,两种涂层组织结构致密,与基体呈良好的冶金结合,并在涂层内形成了纳米晶的微观组织。复合涂层中FeCr_(0.29)Ni_(0.16)C_(0.06)韧性相含量增加,在涂层界面处存在过渡层Ni,并以塑性变形的方式释放了更多沉积时产生的热应力,因而涂层裂纹明显减少。复合涂层的峰值硬度(11.86 GPa)虽略低于单涂层,但该涂层具有最小的摩擦系数(0.2462),1 h磨损量仅为单涂层的1/3,因此表现出更好的耐磨性能,其主要磨损机制为磨粒磨损和疲劳磨损。     

电火花沉积Invar/非晶复合涂层的组织与性能

采用电火花沉积技术在45Mn2钢基材表面沉积了Invar、Invar/非晶及Invar/非晶/Invar涂层,通过X射线衍射仪(XRD)、扫描电镜(SEM)、摩擦磨损试验仪和电化学工作站等分析了沉积层的组织结构、摩擦磨损和电化学腐蚀性能。结果表明,制备的涂层致密、均匀,与基材呈冶金结合。采用Invar合金打底,获得了约60 μm厚度的无显著裂纹Invar/非晶/Invar涂层。Invar涂层为FCC固溶体结构,Invar/非晶和Invar/非晶/Invar涂层为非晶/固溶体复相结构。Invar、Invar/非晶和Invar/非晶/Invar沉积层的平均硬度分别为176.6、 757.7和772.8 HV0.1,摩擦因数分别为0.44、0.21和0.19。提高沉积层非晶含量可提高硬度,降低摩擦因数,提高耐磨性。沉积层在3.5%NaCl溶液中没有明显的钝化现象,Invar、Invar/非晶及Invar/非晶/Invar涂层的自腐蚀电位分别为-0.74、 -0.54、-0.34和-0.31 V,自腐蚀电流密度分别为7.08、5.15、3.78和3.11 μA·cm^-2。电火花沉积的Invar/非晶/Invar涂层致密、均匀、无裂纹,可极大提高45Mn2钢基体表面的耐磨及耐蚀性能。     

激光比能对Fe2B激光熔覆涂层微观组织与性能的影响

利用粉末喷射激光熔覆以球形硼铁粉末为原材料成功制备了 Fe₂B 金属间化合物涂层。 采用金相显微镜 (OM)、 X 射线衍射仪 (XRD)、 扫描电镜 ( SEM)、 电子探针 (EPMA)、 显微维氏硬度计及摩擦磨损试验机对涂层的组织与性能进行了表征。 结果表明: 当激光比能控制在 3. 00×10 ⁸ kJ/ m ² 左右时, 采用粉末喷射激光熔覆能制备较为理想的 Fe₂B 金属间化合物涂层。 制备的单层涂层的物相为 Fe₂B 与 Fe, 显微硬度峰值达 1360 HV_{0. 05} , 涂层组织中大量弥散分布的 Fe₂B 相的生成是涂层具有高硬度的原因。 制备的多层涂层与基体具有良好的冶金结合, 从基体到涂层, 组织经历了一个由平面外延生长组织到胞状晶再到等轴晶的演变过程, 涂层稳定摩擦因数为 0. 385, 磨损率为 5. 67×10 ^-15 m ³ / N·m,表现出良好的耐磨性能, 磨损机制为磨粒磨损与疲劳磨损。     

Electrodeposition of sol-enhanced nanostructured Ni-TiO2 composite coatings

A novel electroplating method has been developed to produce nanocrystalline metal-matrix nano-structured composite coatings. A small amount of transparent TiO₂ sol was added into the traditional electroplating Ni solution, leading to the formation of nanocrystalline Ni-TiO₂ composite coatings. These coatings have a smooth surface. The Ni nodules changed from traditional pyramid-like shape to spherical shape. The grain size of Ni was also significantly reduced to the level of 50 nm. It was found that the amorphous anatase TiO₂ nano-particles (∼ 10 nm) were highly dispersed in the coating matrix. The microhardness was significantly increased from 320 HV₁₀₀ of the traditional Ni coating to 430 HV₁₀₀ of the novel composite coating with 3.26 wt.% TiO₂. Correspondingly, the wear resistance of the composite coating was improved by ∼ 50%.     

Microstructure and Wear Resistance of Fe-Based Amorphous Metallic Coatings Prepared by HVOF Thermal Spraying

Amorphous metallic coatings with a composition of Fe₄₈Cr₁₅Mo₁₄C₁₅B₆Y₂ were fabricated by means of high velocity oxygen fuel (HVOF) thermal spraying process. The microstructure and wear performance of the coatings were characterized simultaneously in this article. It is found that the coatings present a dense layered structure with the porosity below 1.5%. The coatings primarily consist of amorphous matrix and some precipitated nanocrystals, though a fraction of Fe-rich phases and oxide stringers also formed during deposited process. High thermal stability enables the amorphous coatings to work below 920 K temperature without crystallization. Depending on the structural advantage, the amorphous coatings exhibit high average microhardness of 997.3 HV_0.2, and excellent wear resistance during dry frictional wear process. The dominant wear mechanism of amorphous coating under this condition is fatigue wear, leading to partial or entire flaking off of the lamellae. In addition, the appearance of oxidative wear accelerates the failure of fatigue wear.     

A novel electroless plating of Ni-P-TiO2 nano-composite coatings

A new processing concept has been developed to produce nano-structured metal-matrix composite coatings. This method combines sol-gel and electroless plating techniques to prepare highly dispersive oxide nano-particle reinforced composite coatings. Transparent TiO₂ sol was added into the standard electroless plated Ni-P solution at a controlled rate to produce Ni-P-TiO₂ nano-composite coatings on Mg alloys. The coating was found to have a crystalline structure. The nano-sized TiO₂ particles (∼ 15 nm) were well dispersed into the Ni-P coating matrix during the co-deposition process. This technique can effectively avoid the agglomeration of nano-particles in the coating matrix. As a result, the microhardness of the composite coatings were significantly increased to ∼ 1025 HV₂₀₀ compared to ∼ 710 HV₂₀₀ of the conventional composite coatings produced with solid particle mixing methods. Correspondingly, the wear resistance of the new composite coatings was also greatly improved.     

Microstructure and Wear Performance of Arc Sprayed Fe-FeB-WC Coatings

Two Fe-FeB-WC coatings were deposited on the Q235 steel substrate by arc spraying. The microstructure and the abrasive wear performance of the coatings were characterized by x-ray diffraction (XRD) and scanning electron microscope (SEM). The wear mechanisms of the coatings were examined. It was found that Fe-Cr alloy and Fe₂B are present in the coating as the main phases. The results showed that adding hard particle powders could obviously increase the hardness and wear resistance of the coatings. The average microhardness of the coatings was about 870 to 920 HV_0.1. The coatings exhibited excellent abrasive wear resistance, being 3.3 to 4.8 times higher than that of arc sprayed 3Cr13 coating.