以TC4钛合金粗粉为原料不同工艺制备涂层的耐腐蚀与耐磨性能

以粒径为53~106μm的TC4钛合金粗粉为原料,分别采用超音速火焰喷涂、大气等离子喷涂、激光熔覆及对超音速火焰喷涂涂层进行激光重熔等4种工艺在AA1060铝基体和Q235钢基体表面制备TC4钛合金涂层,对比研究了不同工艺下涂层的物相组成、微观结构、耐腐蚀性能与耐磨性能。结果表明:超音速火焰喷涂涂层和大气等离子喷涂涂层主要以α相为主,等离子喷涂涂层还含有一定量的TiO相,这2种涂层与基体的结合方式为机械结合,孔隙率较高;铝基体表面激光熔覆涂层和激光重熔超音速火焰喷涂涂层的主要物相为α相,而Q235钢基体表面则为β相,这2种涂层与基体的结合方式均为冶金结合,结构更加致密,晶粒更加细小,孔隙率极低。大气等离子喷涂涂层的平均硬度可达476 HV,约为超音速火焰喷涂涂层的2倍,激光熔覆涂层和激光重熔超音速火焰喷涂涂层的平均硬度分别超过550,600 HV;Q235钢基体表面涂层的硬度高于铝基体表面的涂层。大气等离子喷涂涂层的平均结合强度均约为30 MPa,比超音速火焰喷涂涂层高30%以上。在质量分数3.5%NaCl溶液中4种涂层按照自腐蚀电流密度从小到大的顺序依次为激光熔覆涂层、大气等离子喷涂涂层、激光重熔超音速火焰喷涂涂层、超音速火焰喷涂涂层。在铝基体表面,激光熔覆涂层的摩擦因数最小,大气等离子喷涂涂层的磨损率最小;在钢基体表面,激光重熔超音速火焰喷涂涂层的摩擦因数最小,激光重熔超音速火焰喷涂涂层和大气等离子喷涂涂层的磨损率相近,且小于其他2种涂层。大气等离子喷涂技术在采用粗粉制备TC4钛合金涂层方面具有最佳的性能与成本优势。

平环强磁选机聚磁介质齿板开发研究

选用酒钢自产含碳量低,含铬量适中的超纯铁素体不锈钢,通过改良工艺、自行研制、加工平环强磁选机聚磁介质齿板开发出一种导磁性能好,工作场强高,耐磨、耐腐蚀性能好,分选指标优良的聚磁介质齿板。完成新开发聚磁介质齿板实验室、生产现场导磁性能、选别指标测试试验。在精矿品位相当的前提下,新开发聚磁介质齿板平均金属回收率比外购聚磁介质齿板金属回收率提高4.36个百分点。

医用钛及钛合金表面微弧氧化膜层性能研究进展

介绍了微弧氧化技术特点,分析了影响钛及钛合金微弧氧化陶瓷膜层的主要特性,指出膜层的耐磨、耐腐蚀性及良好的生物活性是未来医用钛合金微弧氧化表面改性技术的研究重点,最后对微弧氧化技术在医用钛合金表面改性领域的发展进行了展望。

激光技术在材料表面改性方面的研究进展

阐述了激光技术在材料表面改性方面的研究进展,介绍了激光表面重熔(LSM)、激光表面熔覆(LC)及激光表面合金化(LSA)对基材表面组织及性能的影响。相比传统的表面处理技术,激光表面改性技术显著的提高材料的耐磨、耐腐蚀性能,延长工件的使用寿命和服役时间并展望了激光表面改性技术未来的发展前景和经济效益。

电沉积镍基复合镀层的研究进展

电沉积法是目前制备镍基复合镀层的重要方法。介绍了不同电沉积法的特点,综述了电流密度、镀液pH、表面活性剂、第二相颗粒含量和尺寸等工艺参数对镍基复合镀层质量的影响,总结了镍基复合镀层的种类及应用现状,最后对电沉积镍基复合镀层的未来发展方向进行了展望。

Effect of standard heat treatment on microstructure and properties of borided Inconel 718

Boronizing was applied to Inconel 718. In order to obtain the optimal combination of strength and ductility, the borided Inconel 718 was subjected to standard heat treatment. This consists of solution treatment and then a two-step aging treatment. The borided layer is composed of the compound layer and the boron diffusion zone. Because of the superior hardness of borides, the borided Inconel 718 exhibits a significant reduction in its wear rate and relatively low coefficient of friction （COF） compared with the unborided Inconel 718. The standard heat treatment efficiently promotes the diffusion of boron into the interior of the material and the generation of new borides （Fe2B, CrB）. The borided layer with standard heat treatment shows much better wear resistance due to the thicker borided layer （313.76 μm）.

Effect of current frequency on properties of coating formed by microarc oxidation on AZ91D magnesium alloy

The microarc oxidation（MAO） coatings produced at different current frequencies on AZ91 D magnesium alloys were studied systematically. The morphologies, thickness, corrosion performances, and tribological properties of the coatings were investigated by the scanning electron microscopy, the electrochemical measurement system, and MS-T3000 friction test rig, respectively. The results show that the structure of the coatings becomes denser, and thickness becomes thinner with the increase of the current frequency. It is also found that the corrosion resistance of the coatings produced at higher frequency is improved greatly and the difference of the corrosion current density becomes small with increasing current frequency, which is similar to that of the coating thickness. The tribological test shows that the friction coefficient decreases with increasing the current frequency and the wear resistance of the coatings is influenced by both the thickness and structures. All these results were explained by analyzing the growing process of the MAO coating.

Reactive HVOF sprayed TiN-matrix composite coating and its corrosion and wear resistance properties

TiN-matrix composite coating was prepared on 45# steel by reactive high-velocity oxy-fuel （HVOF） spraying. Its microstructure, phase composition, micro-hardness, corrosion resistance in 3.5% NaC1 solution and wear resistance were analyzed. The results suggest that the TiN-matrix composite coating is well bonded with the substrate. The micro-hardness measured decreases with the increase of applied test loads. And the micro-hardness of the coating under heavy loads is relatively high. The TiN-matrix composite coating exhibits an excellent corrosion resistance in 3.5% NaC1 solution. The corrosion potential of coating is positive and the passivation zone is broad, which indicates that the TiN-matrix composite coating is stable in the electrolyte and provides excellent protection to the substrate. The wear coefficient of the coating under all loads maintains at 0.49-0.50. The wear mechanism of the coating is revealed to be three-body abrasive wear. Yet the failure forms of TiN-matrix composite coating under different loads have an obvious difference. The failure form of coating under light loads is particle spallation due to the stress concentration while that of coating under heavy loads is crackin~ between inter-lamellae.

溶胶增强的化学Ni-P-SiO_2复合镀层

采用在基础Ni-P镀液中直接加入溶胶SiO_2的新形式,结合溶胶-凝胶法和化学镀方法,于45钢基材表面成功制备了均匀的复合Ni-P-SiO_2镀层,对比研究了复合镀层与基础Ni-P镀层的显微组织结构、耐磨及耐腐蚀性。结果表明,加入溶胶SiO_2所制备的复合镀层较Ni-P镀层具有更加均匀、致密的显微形貌。当SiO_2溶胶加入量为2.1×10^(-3) mol/L、煅烧温度为400℃时,复合镀层具有最高显微硬度值668.54 HV_(0.025),最低摩擦系数0.279,最正腐蚀电位-0.449 7 V及最小腐蚀电流0.632 7×10^(-6) A·cm^(-2)。说明以该方法所制备的复合Ni-P-SiO_2镀层具有良好的耐磨、耐腐蚀性能,节省SiO_2原料用量,且不需要额外加入分散剂与稳定剂,减少长时间搅拌的能耗,对实际工业生产大有裨益。

Microstructure and properties of laser cladding of 316L stainless steel on hydraulic support tube

In consideration of the special environmental conditions of coal equipment in mining, the seamless steel tube of hy-draulic prop made of 20^# carbon steel was taken as the substrate, and 316L stainless steel powder was used to clad the sub-strate by a fiber-coupled semiconductor laser. The microstructure of the cladding layer was determined by metalloscope. The hardness, wear resistance and corrosion resistance of the cladding layer were measured. The results show that metallurgy bind-ing interface between the cladding layer and the substrate is obtained without defects such as cracks and pores. The hardness of the cladding layer is much higher than that of the matrix, and the wear resistance and corrosion resistance are simultaneously better. According to the analysis, it is summarized that the improvement in performance of the cladding layer is closely related to the change of microstructure and the thermal effect in the cladding process. The maximum hardness occurs in the equiaxed zone, and with the grain coarsening, the hardness reduces simultaneously. In addition, the precipitated phase, hard particles and trace elements also have a great influence on the properties of the cladding layer, and they will prevent the surface from ab-rasion and reduce the plastic deformation of the matrix. It is verified that the 316L stainless steel is suitable for the 20^# steel in laser cladding repairing process. Since this study focused on coal machine equipment parts, it has certain practical significance for the repair of hydraulic equipment.

Tribological and corrosion behavior of PEO coatings with graphite nanoparticles on AZ91 and AZ80 magnesium alloys

The effect of the addition of graphite nanoparticles into the electrolyte used to produce plasma electrolytic oxidation（PEO） coatings on AZ91 and AZ80 magnesium alloys was studied. The corrosion and wear resistances of the obtained coatings were investigated. A solution that contained both phosphates and silicates was used as electrolyte. Moreover, two different PEO treatment times were studied. The corrosion resistance was analyzed with potentiodynamic polarization and EIS tests; the wear resistance was investigated with a flat on ring tribometer. The results were related to the morphology, microstructure, elemental composition and thickness evaluated with SEM analysis. The presence of the graphite nanoparticles increased the thickness, produced a densification of the coating and sealed the pores on the surface, thus improving both the corrosion and wear resistance. The increase in the corrosion and wear resistances was more evident for AZ91 than for AZ80 due to the higher aluminum content.

镁合金上化学Ni-P-硬质氧化物复合镀层

结合溶胶-凝胶法和化学镀方法,于镁合金基材表面成功制备了均匀的复合Ni-P-SiO2/TiO2/Al2O3镀层,采用扫描电镜(SEM)、光学显微镜(OM)、摩擦磨损试验及电化学方法,对比研究了Mg基材、基础Ni-P镀层与3种复合镀层的显微组织结构、耐磨性及耐腐蚀性。结果表明,加入3种溶胶所制备的复合镀层较Mg基材大幅度提高耐磨性和耐腐蚀性;3种复合镀层较Ni-P镀层具有更加均匀、致密的显微形貌,减少了直接加入纳米粉末的团聚,同时耐磨和耐蚀性改善。其中Ni-P-SiO2复合镀层具有较高的显微硬度(HV513)和最低的摩擦系数(0.34),最高的腐蚀电位(-1.18V)及较小的腐蚀电流密度(9.5×10^-3mA·cm^-2)。综合制备最佳工艺,并考虑节能减排因素,Ni-P-SiO2复合镀层可作为性能优良的Mg合金耐磨、耐腐蚀镀层使用,于实际工业生产大有裨益。