Исследовано влияние различного количества добавок керамических частиц WC на микроструктуру и эксплуатационные свойства покрытий Stellite 6, наплавленных лазером на поверхность стали 17-4PH (09Х17Н7Ю1). Изучено поведение таких покрытий в условиях горячей коррозии при 350 °C. Установлено, что с увеличением содержания WC средняя твердость покрытия сначала увеличивается, а затем уменьшается. По сравнению со стальной подложкой максимальное повышение средней твердости покрытия составило 49,99 %. Добавление WC значительно снижает скорость износа покрытия, наименьшее значение которой составило 4,06936 × 10 – 7 г/(Н × м). При увеличении количества WC коррозионная стойкость покрытия показала тенденцию сначала к увеличению, а затем к уменьшению. Сравнение поведения покрытий Stellite 6 и 30 % WC – Stellite 6 при горячей коррозии показало, что в обоих случаях в их структуре наблюдались фазы CoO и Cr2O3, но покрытие 30 % WC – Stellite 6 содержало также фазы CoWO4 и Fe2O3. Основным механизмом коррозии является окисление. Полученные экспериментальные результаты позволяют повысить эксплуатационные свойства покрытий уплотнительных поверхностей клапанов ядерной энергетики и увеличить срок их службы в жестких условиях эксплуатации.

FeCoNiCuAl high-entropy alloys exhibit remarkable mechanical properties; nevertheless, these materials struggle to withstand harsh environments because of their insufficient resistance to wear and corrosion. The addition of Si can significantly enhance the alloy’s high-temperature performance, hardness, and wear resistance, thereby making it more suitable for applications in high-temperature or corrosive environments. To overcome these drawbacks, this research investigates how varying Si content affects the microstructure and properties of FeCoNiCuAl coatings. Composite coatings of FeCoNiCuAlSix (x = 0, 0.5, 1.0, 1.5, 2.0) were fabricated on 65 Mn substrates using laser cladding. Various testing methods, including metallographic microscopy, Vickers hardness testing, friction and wear testing, and electrochemical analysis, were employed to examine the phase structure, microstructure, and hardness of the coating. It is observed that the FeCoNiCuAl coating begins with a uniform FCC phase structure. However, as the Si content increases, a phase transformation to the BCC structure occurs. The microstructure is primarily composed of isometric crystals and dendrites that become finer and more compact with higher Si content. For the FeCoNiCuAlSi2.0 coating, the microhardness reaches 581.05 HV0.2. Additionally, wear resistance shows a positive correlation with Si content. Electrochemical testing in NS4 solution shows that the corrosion potential of the coating increases from −0.471 V for FeCoNiCuAl to −0.344 V for FeCoNiCuAlSi2.0, while the corrosion current density decreases from 1.566 × 10−6 A/cm2 to 4.073 × 10−6 A/cm2. These results indicate that Si addition plays a crucial role in enhancing the mechanical properties and corrosion resistance of FeCoNiCuAl coatings, making them more suitable for high-performance applications in extreme environments.

An ultrasonic residual amplitude coefficient model is proposed for optimally estimating the lubricant film thickness at coated interfaces with unidentified coating thickness. The residual amplitude coefficient is defined as a function of the lubricant film thickness rather than the coating thickness, which eliminates the influence of the coating-induced phase shift. The minimum root mean square of the residual amplitude coefficient is utilized to determine the lubricant film thickness. Both the simulation and test results show that at different coated interfaces, the proposed model is capable of determining the lubricant film thickness in a wide range from 1 mu m to 95 mu m. The relative errors are less than 11.3 %.

为提高金属陶瓷涂层与基体的结合性能,通过对Ni-WC金属陶瓷涂层实施电阻加热和超声深滚耦合处理,探究高温环境下不同超声深滚静压力对Ni-WC金属陶瓷涂层微观组织结构的影响.通过扫描电镜、X射线衍射仪和JADE软件对改性金属陶瓷涂层进行测试,通过分析改性金属陶瓷涂层的表面微观形貌、晶粒尺寸和表面残余应力,探讨改性金属陶瓷涂层结合强度,用ImageJ软件评价改性金属陶瓷涂层孔隙率.结果表明:高温下超声深滚提高了涂层表面光洁度,细化了晶粒,引入了残余压应力,提高了涂层综合性能;随静压力的增大,改性金属陶瓷涂层的表面微观形貌得到明显改善,表面残余压应力逐渐增大,涂层与基体之间形成了部分冶金结合,结合强度大大提高;静压力较大时出现了物相的转变,且随静压力的增大,其孔隙率也逐渐减小.

To improve the friction and wear properties of a plasma-sprayed Ni/WC coating on a #45 steel substrate and explore the influence of spindle speed on the friction and wear properties of the coating in the process of hightemperature assisted ultrasonic rolling (HT/USR), The HT/USR processing of the Ni/WC coating was conducted under various spindle speeds (173, 248, and 360 r/min). The results showed that the pores and cracks in the Ni/ WC coating after HT/USR treatment were reduced, giving the coating a compact structure. The surface performance of the coating was the best when the spindle speed was 173 r/min. Compared with the untreated sample, the surface roughness of the coating treated by HT/USR-173 r/min was reduced by 49 %, and the surface hardness was increased by 38.4 %. The residual tensile stress was transformed from tensile stress to compressive stress, reaching 404.2 MPa. The wear mechanism of the coating after HT/USR treatment changed from abrasive and fatigue wear to abrasive and oxidation wear. The friction coefficient and wear amount decreased with decreasing spindle speed. The average friction coefficient and wear amount of the coating with a spindle speed of 173 r/min were the lowest, 0.03094 and 5.4 mg, respectively, which are 69.23 % and 64.23 % lower than those of the untreated sample. Therefore, HT/USR effectively improved the surface properties of the plasma-sprayed Ni/WC coatings, as well as their friction and wear properties.

Cermet coatings are post-treated by a new surface microcrystallization technology, namely high-temperature-assisted ultrasonic deep rolling (HT + UDR). The process parameters of ultrasonic deep rolling significantly affect the microstructure and tribological properties of the Ni-WC coatings. In this paper, the samples were treated with different preloading depths (0.20 mm, 0.25 mm, and 0.30 mm), and the microstructure and properties of the coatings were characterized by SEM, EDS, X-ray stress analysis, and micro-Vickers hardness testing. An MMW-1A-type friction and wear tester was used for the dry friction and wear test at room temperature, respectively. Compared with the untreated sample, plastic rheology occurred on the surface of the coatings after HT + UDR, showing a phenomenon of “cutting peaks and filling valleys”. In the treated coatings, visible cracks were eliminated, and the inside of the coating was denser. The surface hard phase was increased as a “skeleton” and embedded with the soft phase, which played a role in strong and tough bonding. After HT + UDR + 0.25 mm treatment, the surface roughness increased by 68%, the microhardness of the surface layer reached a maximum of 726.3 HV0.1, and the residual tensile stress changed from 165.5 MPa to −337.9 MPa, which inhibited the germination and propagation of cracks. HT + UDR improved the wear resistance of the coating in many aspects. The coating after the 0.25 mm preloading depth treatment possessed the smallest friction coefficient and the lowest wear amount, which is 0.04 and 4.5 mg, respectively. The wear form was abrasive wear, and the comprehensive tribological performance is the best.

超声滚压表面强化技术是一种新型的材料表层后处理工艺,利用预置初始静压力和动态超声冲击力耦合的方式对材料表层进行往复加工,从而达到"削峰填谷"的光整效果,获得更深的表面纳米硬化层和有益的残余应力.首先介绍了超声滚压技术的加工原理和特点,然后从试验影响参数、数值模拟、性能应用、复合加工工艺等几个方面总结了超声滚压技术的研究进展,其中工艺参数(静压力、超声振幅、主轴转速、进给速度、进给量、滚压次数和覆盖率)的择优对材料组织与性能之间的调控效果具有明显改善作用,通过对试验研究中的工艺进行数值模拟,选取优化的工艺参数可以获得较好的材料表面完整性.重点综述了超声滚压处理对金属材料在耐磨性和耐疲劳性能等方面的改善效果,以及其他工艺辅助超声滚压技术对材料性能提升的协同调控作用,通过对超声滚压工艺参数的合理选择,能够实现材料表面纳米结构的形成、有益残余应力的转化和表面显微硬度的提升等方面的协同效果,从而改善材料的微观组织形貌、耐磨性、耐冲蚀性和耐腐蚀性等.最后总结了现有超声滚压表面强化技术存在的不足,并对今后的研究方向进行了展望,即进一步结合工程产品需求和应用领域进行技术创新,进而推动超声滚压表面强化技术的持续发展.

为进一步改善等离子喷涂Ni/WC涂层的组织性能,采用高温辅助超声滚压(HT+USRP)对其进行处理,采用维氏硬度计、扫描电镜和X射线衍射仪等分析了处理后Ni/WC涂层的组织性能,并研究了超声滚压过程中主轴转速对Ni/WC涂层组织性能的影响.结果表明:主轴转速主要影响HT+USRP涂层表面在周向方向上的加工均匀性.当主轴转速较低时,涂层塑性变形比较均匀,软化的涂层在力的挤压下能更好地填充到孔隙和裂纹中;而在较高主轴转速时,会出现加工跳跃现象,导致涂层表面塑性变形不均匀.Ni/WC涂层经HT+USRP处理后,与低主轴转速时处理的涂层相比,高主轴转速时处理的涂层孔隙率更高,显微硬度和残余应力更小.当其他工艺参数一定,主轴转速为176 r/min时,涂层的组织性能最好,孔隙率降至3.67％,表面显微硬度为687.3 HV0.2,表面残余压应力为-404.2 MPa.

The effect of ageing on the structure and mechanical properties of continuously cast and rolled sheet from aluminum alloy 6061 is studied. Atreatment regime involving 2-h water quenching from 550°C and six hours artificial ageing at 200°C is shown to provide the values of σr, δ, and HV equal to 318 MPa, 14%, and 127 HV0.1 respectively. The alloy fractures by a ductile mechanism after quenching and by a mixed mechanism after ageing. The average grain size after ageing is 0.09 nm, and over grain boundaries there is a large amount of Mg2Si nanosize inclusions and heat-resistant α-Fe phase that increase sheet mechanical properties.

首先,从热喷涂的后处理技术方向入手,重点综述了激光重熔后处理技术、热处理后处理技术的研究进展,简要分析了两种后处理技术对金属陶瓷涂层界面综合性能、界面结合强度、内聚强度、耐磨性、残余应力等的影响,指出外部因素(激光重熔参数、热处理工艺参数、材料种类、重熔方式和热处理的时间等)和内部因素(金属陶瓷涂层本身的特性)对两种后处理技术的影响.然后,介绍了几种材料后处理技术(喷丸和热等静压后处理技术),分析了其对材料性能的影响.其次从微观层次入手,探索和分析了热喷涂后处理技术的原理和其中存在的问题,且对其研究和发展方向做出了预测.最后,在前人研究的基础上,结合近些年常用的涂层后处理技术和一些材料后处理技术,提出了采用一种新的后处理技术——感应重熔技术和超声深滚技术耦合对喷涂涂层实施后处理,且初步制定了研究的技术方案,并对其特色点和创新之处进行了总结,同时对该研究进行了可行性分析.

A combustible cartridge is made of nitrocellulose, wood fibers and resin. It is easy to absorb moisture in a high-humidity environment and the NC-based materials may self-ignite after storage at higher temperature for a long time. A large number of studies have been carried out to improve the surface protection performance of combustible cartridges usually using a general nitrocellulose varnish. But the heat-resistance of the nitrocellulose varnish coating is poor. In this article, we develop a composite coating that improves the heat-resistance and salt wet resistance of combustible cartridges. The new composite coating was prepared by adding BN/silane composite particles and non-ionic surface active reagent Tween 80 into the nitrocellulose varnish by an optimized composition. The high temperature resistant performance and salt tolerance properties effect of the new composite coating for combustible cartridge were investigated by thermogravimetric experiment, muffle furnace experiment and salt wet resistance test. Compared with the control sample, the coated sample by the new composite coating was able to stand for 138 s at a high temperature of 220 degrees C, increasing the high temperature resistance time by a maximum percentage of 50 %. In a high-salt environment, the final water absorption percentage was only 0.2944 % when the coated sample is immersed in a high salt content water at 26 degrees C for three days, increasing the salt wet resistance by a maximum percentage of 70 %. Results show that the new coating using BN/silane composite particle can improve the high temperature resistant performance and salt tolerance properties of combustible cartridges effectively.