硬质颗粒对等离子熔覆碳化钨/多主元合金复合硬面涂层组织与耐磨性能的影响

采用等离子熔覆技术制备分别以铸造WC颗粒和烧结WC-Co球粒为硬质颗粒、以多主元合金为黏结相的2种硬面复合涂层,采用X射线衍射仪、扫描电镜、摩擦实验等手段,研究不同硬质颗粒对硬面复合涂层组织和耐磨性能的影响。结果表明:FeCrNi/WC-Co复合涂层中M6C的体积分数为20.1%,低于FeCrNi/WC复合涂层中M6C的体积分数(28.4%)。烧结WC-Co颗粒的热力学稳定性高,其WC的溶解程度低于铸造WC颗粒,可有效减少脆性M6C碳化物的析出。FeCrNi/WC-Co复合涂层的耐磨性能优于FeCrNi/WC涂层。FeCrNi/WC-Co涂层中较少的M6C相可避免涂层因脆性断裂而过早剥落,保证硬质相颗粒的完整性,提升硬面涂层的耐磨性能。

钢材用激光熔覆硬面涂层工艺及其实验研究

为了提升钢铁的耐磨性与耐腐蚀性,提出了一种钢材用激光熔覆硬面涂层工艺。该工艺利用激光熔覆技术将金属陶瓷涂层与钢铁基体冶金结合。实验证明,利用该工艺后,钢铁耐磨性、耐腐蚀性提升3~6倍,其抗冲击性不受影响。同时,其基础材料与生产工艺兼具低成本及环保的特点,是一种具有国内外领先,并具有良好发展前景的增材制造技术。

镍基-碳化铬硬面复合涂层的疲劳强度

采用真空熔覆方法,在Q235 A试样表面制成厚0.1mm的镍基 碳化铬硬面复合涂层。通过试验比较涂层试样与无涂层试样的疲劳寿命。借助测量结合界面附近的化学成分,不仅得到了涂层与母材之间的元素扩散情况,而且能够分析界面的结合强度。

Al_2O_3-M_xO_y硬面陶瓷涂层的喷焊制备及性能研究

在碳钢母材上 ,用氧乙炔焰喷焊镍包铝合金粉末制取预涂层 ,喷焊 5 0 %Al2 O3 +5 0 %Ni的复合粉末制取过渡层 ,用等离子喷焊Al2 O3 -MxOy 复合粉末制取最终涂层。在质量分数为 6 0 %的硫酸与磷矿粉组成的混合介质 (质量比为 6∶4 )中运转 ,所获得涂层的抗腐抗磨能力为 18- 8不锈钢的 7 4 6倍 ,为德产 316L不锈钢的4 0 6倍。

激光熔覆法制备WC-Co球粒强化高熵合金复合硬质涂层的组织与性能

在FeCoCrNiMo0.15高熵合金(high entropy alloy,HEP)粉末中分别添加WC和WC-Co硬质相球粒,然后采用激光熔覆法在304不锈钢基材上制备2种以Fe Co Cr Ni Mo0.15高熵合金为基体的硬质复合涂层WC/HEA和WC-Co/HEA,研究这2种复合涂层的微观组织、硬度、耐磨与耐蚀性能,并与真空扩散焊制备的Ni60/WC复合涂层性能进行对比。结果表明,WC-Co/HEA涂层中WC颗粒的球形度高,涂层内气孔和裂纹较少,添加Co元素可有效避免激光熔覆过程中WC发生分解。WC/HEA和WC-Co/HEA复合涂层的平均显微硬度(HV)都在800MPa以上,其中WC-Co/HEA涂层的平均显微硬度(882.55MPa)高于WC/HEA涂层的硬度(817.27MPa),且其平均摩擦因数(0.40)略低于WC/HEA涂层(0.46)。与Ni60/WC涂层相比,HEA基涂层对WC的保持性和润湿性更好,能降低涂层与WC之间的界面反应,因此WC-Co/HEA复合涂层的显微硬度、摩擦磨损性能、耐蚀性能均优于Ni60/WC和WC/HEA涂层。

Sliding wear characteristics of solid lubricant coating on titanium alloy surface modified by laser texturing and ternary hard coatings

Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because ofits severe adhesive wear tendency.The surface modifications through texturing and surface coating were used to enhance the surfaceproperties of the titanium alloy substrate.Hard and wear resistant coatings such as TiAlN and AlCrN were applied over texturedtitanium alloy surfaces with chromium as interlayer.To improve the friction and wear resisting performance of hard coatings further,solid lubricant,molybdenum disulphide(MoS2),was deposited on dimples made over hard coatings.Unidirectional sliding weartests were performed with pin on disc contact geometry,to evaluate the tribological performance of coated substrates.The tests wereperformed under three different normal loads for a period of40min at sliding velocity of2m/s.The tribological behaviours ofmulti-layer coatings such as coating structure,friction coefficient and specific wear rate were investigated and analyzed.The lowerfriction coefficient of approximately0.1was found at the early sliding stage,which reduces the material transfer and increases thewear life.Although,the friction coefficient increased to high values after MoS2coating was partially removed,substrate was stillprotected against wear by underlying hard composite layer.

Investigation of MQL-Employed Hard-Milling Process of S60C Steel Using Coated-Cermented Carbide Tools

The application of cutting fluids in machining brings out many benefits, but their use is accompanied by health and enviroment hazards. MQL （Minimum Quantity Lubricant） has become a preciously alternative solution for lubrication against dry machinning and flood cooling lubricant, and this is a step toward green machining. This paper presents a comprehensively experiemental study on investigation of MQL performance in hard milling of S60C steel for multiple responses, including surface quality, cutting forces and tool wear. Compared to dry milling, even-enhanced surfaces finish quality, 20% less cutting force （Ft） and almost 112% prolonged tool lifetime are achieved by using MQL with 5% Emulsion in hard milling. In addition, this study compared the performances of MQL milling by using 5% Emulsion to the peanut oil completely harmless to the enviroment. This encouraging result, therefore, reveals that the MQL-employed hard milling can enable significant improvement in productivity, product quality, and overall machining economy even after covering the additional cost of designing and implementing MQL system. Moreover, this study also shows the limitation of peanut oils employed in MQL and proposes the further research in novel additives to enhance the performance of cooling lubricant for vegetable oils.

超音速火焰喷涂WC-12Co、WC-10Co4Cr和Cr_(3)C_(2)-25NiCr涂层在不同介质中摩擦行为研究

为了研究硬面涂层在不同介质中的摩擦行为,以WC-12Co、WC-10Co4Cr和Cr_(3)C_(2)-25NiCr硬面材料为原料,采用超音速火焰喷涂(HVOF)技术制备得到了3种不同成分的硬面涂层。通过显微硬度计、摩擦磨损仪和扫描电镜等对涂层的硬度及摩擦磨损形貌进行分析。结果表明,涂层中的孔隙率和粘结相的含量密切相关,当粘结相质量分数为12%(Co)时,其孔隙度为1.11%;粘结相质量分数为14%(CoCr)时,其孔隙度为0.98%;粘结相质量分数为25%(NiCr)时,其孔隙度降低为0.92%。空气中,WC-10Co4Cr的硬度最高,其摩擦系数最小;Cr_(3)C_(2)-25NiCr的硬度最小,其摩擦系数最大。1mol/L HCl的环境中,NiCr的耐腐蚀性能最好,使Cr_(3)C_(2)-25NiCr涂层的摩擦系数稳定;而纯Co和CoCr的耐腐蚀性能较差,使WC-10Co4Cr和WC-12Co涂层的摩擦系数呈现出波浪状的变化规律。1mol/L NaOH的环境的摩擦过程中,硬质相的腐蚀会使涂层表面的硬度下降,使摩擦系数增加。

Slurry erosion behaviors of P110 steel and chromizing coating in liquid-solid two-phase flow

A chromizing coating was formed on P110 oil casing tube steel (P110 steel) via pack cementation to improve its performance and increase the lifetime during operation. The slurry erosion behaviors of the P110 steel substrate and the chromizing coating were assessed in a liquid-solid two-phase flow condition. The results showed that the obtained coating exhibited higher surface hardness, lower mass loss, and lower slurry erosion rate than those of P110 steel. The chromizing treatment has significantly improved the surface hardness and slurry erosion resistance of P110 steel.