铸钢表面电火花沉积层摩擦磨损性能

采用新型电火花沉积设备,把WC-4Co陶瓷硬质合金材料沉积在铸钢材料上,制备了电火花沉积合金涂层,用SEM、XRD等技术研究了沉积层的物相、微观组织结构、元素分布、显微硬度及室温高温耐磨性能及磨损机理。结果表明:沉积层主要由Fe3W3C、Co3W3C和Fe2C等相组成;沉积层与基体呈冶金结合,过渡层出现一些柱状晶和树枝状晶组织结构,沉积层中细小的Fe3W3C和Co3W3C等硬质相颗粒弥散分布于Fe2C基体上。沉积层的平均显微硬度为1803.2 HV;室温下沉积层的耐磨性和300℃高温条件下沉积的耐磨性分别比同样条件下铸钢材料的磨损性能提高了2.5倍和3.4倍;不论室温还是300℃高温条件下沉积层的磨损机理主要是粘着磨损、疲劳磨损、氧化磨损和磨粒磨损的综合作用,细小的弥散分布的硬质相是沉积层硬度及耐磨性提高的主要因素。     

铸钢表面电火花沉积WC-8Co涂层的高温性能

采用新型电火花沉积设备,把WC-8Co陶瓷硬质合金材料沉积在铸钢材料上,制备了电火花沉积合金涂层,用SEM、XRD等技术研究了沉积层在500℃的高温耐磨性和800℃高温氧化100 h后氧化膜形貌图、组织结构和高温抗氧化性能。结果表明:沉积层厚度为20~30μm。500℃高温条件下沉积层的耐磨性比基体提高了3.3倍,500℃高温条件下沉积层的磨损机理主要是粘着磨损、疲劳磨损、氧化磨损和磨粒磨损的综合作用。800℃高温条件下沉积层氧化100 h后的氧化膜的厚度约为10μm;氧化膜主要由FeFe_2O_4、Fe_2O_3、Fe_5C_2和Fe_2W物相组成;800℃高温下沉积层抗氧化性能比基体的抗氧化性能提高了4.8倍。细小弥散分布的硬质相和致密的氧化膜极大提高了沉积层的抗高温磨损性能和抗高温氧化性能。     

铸钢轧辊亚微米WC-15Co电火花沉积涂层的高温性能

采用新型电火花沉积设备,把WC-15Co陶瓷硬质合金材料沉积在铸钢材料上,制备了电火花沉积合金涂层,用SEM、XRD等技术研究沉积层在500℃的高温耐磨性和800℃高温氧化100 h后的氧化膜形貌、组织结构和高温抗氧化性能。结果表明:沉积层厚度约为30μm。500℃高温条件下,沉积层的耐磨性比基体的耐磨性提高2.7倍,沉积层的磨损机理主要是粘着磨损、疲劳磨损、氧化磨损和磨粒磨损的综合作用;800℃高温条件下,沉积层氧化100 h后的氧化膜的厚度约为10~30μm,氧化膜主要由FeFe_2O_4、W_(20)O_(58)和CFe_(2.5)物相组成,沉积层的抗氧化性能比基体的提高3.6倍。细小弥散分布的硬质相和致密的氧化膜极大提高沉积层的抗高温磨损性能和抗高温氧化性能。     

铸钢轧辊电火花沉积WC-4Co涂层组织和性能分析

采用新型电火花沉积设备,把陶瓷WC-4Co电极材料沉积在铸钢轧辊材料上,制备了WC-4Co沉积涂层,研究了其微观组织及耐磨性能.结果表明,沉积层主要由Fe3W3C,Co3W3C,Fe和SiC等相组成;沉积层与基体呈冶金结合,过渡层组织主要是柱状晶结构组织;Fe3W3C和Co3W3C等硬质相弥散分布于沉积层Fe基体上,部分区域硬质相达到了纳米颗粒尺寸;沉积层硬度的平均硬度为1617.2HV;沉积层较铸钢轧辊的磨损性能提高了2.1倍,沉积层的磨损机理主要是粘着磨损、疲劳磨损、氧化磨损和磨粒磨损的综合作用,细小的弥散分布的硬质相是沉积层硬度及耐磨性提高的主要因素.     

电火花沉积与激光熔覆复合涂层的组织与性能

采用激光熔覆工艺和电火花沉积工艺在Q235钢上熔覆铁基合金粉末和WC陶瓷硬质合金,形成复合涂层.采用X射线衍射仪、扫描电镜、显微硬度计等对复合涂层的相结构、显微组织、显微硬度及耐磨性能进行了分析.结果表明:复合涂层主要是由Fe3W3C、Co3W3C、Si2W、W2C和(Fe0.51Mn0.46 Ni0.03)6C等相组成;复合涂层与基体呈冶金结合,复合涂层中电火花区域中细小的硬质相弥散分布于沉积层中;复合涂层的厚度为140～160 μm,其中电火花沉积区域约为40μm,激光熔覆工艺的涂层厚度为100～120 μm;电火花沉积层的硬度最高可达1262.9 HV,平均硬度为1151.6 HV,电火花沉积区域与激光熔覆区域之间的过渡区域的显微硬度为884.8 HV,激光熔覆区域的显微硬度平均值为578.3 HV;复合涂层的耐磨性较基体耐磨性提高2.3倍,强化层的磨损机理主要是磨粒磨损、粘着磨损和氧化磨损.     

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WC-4Co复合层界面行为

采用新型电火花沉积设备,将亚微米WC-4Co陶瓷硬质合金材料沉积在铸钢材料上,制备电火花沉积合金涂层,利用SEM和XRD等技术研究沉积层与基体间的界面行为,分析沉积层的表面润湿性、物相形成机理、微观组织结构、界面元素分布、界面结合机理和显微硬度变化等。结果表明:电火花沉积技术可以在金属基体表面制造出微纳米非晶高熔点强化层。铸钢表面沉积层主要由Fe3W3C、Co3W3C、Si2W和Fe2C等相组成;沉积层与基体呈冶金结合,过渡层中出现一些柱状晶和等轴晶的组织结构,沉积层中细小的Fe2C和Si2W等硬质相颗粒弥散分布于Fe3W3C和Co3W3C沉积层上。沉积层的厚度大于20μm,沉积层的平均显微硬度为1803.2 HV,细小弥散分布的硬质相是沉积层硬度提高的主要因素。     

铸钢0Cr13Ni5Mo表面电火花沉积YG8涂层的组织和性能

采用新型电火花设备在铸钢表面制备了YG8涂层,采用SEM、XRD技术研究其微观组织和耐磨性能。结果表明:沉积层主要由Co3W3C、Fe3W3C、Fe3Mo3C、WC1 x和Fe7W6C等相组成;沉积层与基体冶金结合,细晶碳化物相弥散分布在沉积层中,能提高沉积层的硬度,平均硬度为1 896.8HV,比基体硬度提高了5倍;沉积层磨损性能是基体的3.4倍,沉积层磨损机理主要是粘着磨损、颗粒磨损和氧化磨损的综合作用;沉积时骤热骤冷过程中形成的细晶粒硬质相是提高沉积层硬度和耐磨性的主要因素。     

新型Co-Al-W合金高温氧化行为研究

研究了γ′-Co3(Al,W)相沉淀强化的新型钴基高温合金,Co-Al-W抗高温氧化性能。利用SEM、EPMA、XRD等方法研究了新型Co-Al-W合金在800℃和900℃空气中静态氧化增重动力学和抗高温氧化机理,并与镍基高温合金Manaurite900相比较。研究发现,在800℃氧化时,9.8W合金抗氧化能力最强,但在900℃时,9.8W和7.5W合金的增重最大,Manaurite900和10.7W的抗氧化能力最好。合金在2种温度下氧化后,表面氧化膜主要由三层构成,即Co氧化物Co3O4组成的氧化膜最外层,Co、Al、W复杂氧化物组成的中间过渡层及Al和Co氧化物组成的氧化膜最内层。     

铸钢材料电火花表面沉积WC-4Co涂层的组织与性能

采用电火花沉积工艺,在铸钢表面制备了WC-4Co沉积涂层,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、Fe7W6等相组成;沉积层与基体呈冶金结合,Fe7W6、W2C等硬质相弥散分布于沉积层中,部分区域硬质相达到了纳米颗粒尺寸;沉积层的平均硬度为1517HV0.3,约是基体硬度(502 HV0.3)的3倍;其耐磨性能比基体提高了2.4倍;沉积层的主要磨损机制为疲劳磨损,细小的弥散分布的硬质相是沉积层硬度以及耐磨性能提高的主要因素.     

High Temperature Oxidation and Wear Resistance of Y-modified Hot Dipping Aluminized Coating on SCH12 Steel

Microstructures,high-temperature oxidation and wear resistance of hot dipping Al-Si-Y coating on SCH12 heat resistant cast steel were investigated in this study.The aluminized coating was characterized by scanning electron microscopy(SEM),energy dispersive X-ray spectrometry(EDX)and X-ray diffraction(XRD).The results showed that the coating was composed of the Al-rich outer layer and the intermetallics inner layer.In the Al-rich layer,some Y-rich precipitates and Fe-Al-Si-Cr precipitates could be observed.The intermetallics layer presented three layers induced by the increase of Fe,Cr,Ni content and the corresponding decrease of Al,Si content.The oxidation tests were conducted in still air at 850℃for up to 100 h.After oxidation,a top oxide scale composed of mainlyα-Al2O3,Al5Y3O12 was formed on the steel surface.The intermetallics beneath the oxide scale consisted of mainly FeAl and small amount of Fe2Al5 and Cr3Si phase.The mass gain of the coated and uncoated SCH1steel is 0.45 mg/cm 2 and 0.57 mg/cm 2,respectively.The wear resistance was investigated using a high-temperature pin-on-disc tribometer at 650℃.The wear rate for the coated and uncoated steel is 0.45μm 3 /μm.N and 3.01μm 3 /μm.N,respectively.The high temperature wear tests and oxidation tests results demonstrated that the yttrium-modified aluminized specimen had significantly improved high-temperature wear resistance and equivalent oxidation resistance compared with the original SCH12 specimen.     

含铁铜基陶瓷复合材料高温氧化行为与耐磨性研究

在25,250,350和450℃高温摩擦磨损实验条件下,对两种不同铁含量的Cu基摩擦材料进行高温氧化行为及耐磨性研究。结果表明:Fe在Cu基体中的尺寸、分布影响Cu基摩擦材料的高温抗氧化性和耐磨性,随实验温度升高,Cu基摩擦材料试样中Cu氧化产物为Cu2O,Fe从Fe2O3转变为Fe3O4,金属氧化膜厚度逐渐增加;Fe以小尺寸、均匀分布于Cu基体时,更有利于提高Cu基体整体的抗氧化性能,在350~450℃可形成稳定的氧化膜降低粘着磨损,展现出了较好的高温耐磨性能;而Fe以较大尺寸分布在Cu基体中时,则使Cu基体出现氧化不均匀现象,不利于高温耐磨性能的提高。     

Microstructure and Wear Resistance Evolution of HVOFSprayed WC-（W,Cr）2C-Ni Coating with Post Heat Treatment In Air Atmosphere

WC-(W,Cr)2C-Ni coating was prepared on 1Cr18Ni9Ti stainless steel and C-276 Ni-base Hastelloy by high velocity oxy-fuel(HVOF)spraying.The effect of post heat treatment in air atmosphere on the microstructure,phase composition,microhardness,fracture toughness,and wear resistance of HVOF-sprayed WC-(W,Cr)2C-Ni coating was investigated.The microstructure and phase composition of the coatings were analyzed by means of field emission scanning electron microscopy(FESEM)and X-ray diffraction(XRD).The microhardness and fracture toughness of the coatings were measured using a microhardness tester and a Vickers hardness tester.Moreover,dry friction and wear behavior of the coatings sliding against Si3N4 ball was investigated using an oscillating friction and wear tester;and the worn surfaces of the coatings were analyzed by means of scanning electron microscopy(SEM).It was found that heat treatment within 500-800°C resulted in crystallization of amorphous phase in as-sprayed coating,generating nanoscale new phases such as NiWO4,CrWO4 and Cr2WO6.Besides,heat treatment led to increase of the microhardness of as-sprayed coating,and the highest microhardness was obtained after heat treatment at 800°C.The fracture toughness and wear resistance of the as-sprayed coating increased with increasing heat treatment temperature up to 700°C but tended to decrease with further elevating temperature.In other words,the mechanical properties and wear resistance of the as-sprayed coatings were worsened owing to excessive growth of oxidation grains and depletion of ductile Ni binder after heat treatment above 700°C.Thus it was suggested that as-sprayed ceramic composite coating should be post heat treated in air at a moderate temperature of 700°C so as to achieve the optimized mechanical properties and wear resistance.     

钼合金Si-Cr-Ti-SiC-MnO2涂层的制备与组织性能

目的提高钼合金表面红外辐射性能与高温抗氧化性能。方法将40%Si、20%Cr、5%Ti、5%SiC、30%Mn O_2五种粉末与酒精、粘结剂按比例混合,经高能球磨6 h后制得均匀悬浮的料浆。采用浸涂工艺对预处理的钼合金试样进行料浆涂覆,在1450℃真空烧结0.5 h后制得黑色涂层试样。通过1550℃高温静态氧化试验和高温粒子薄片红外光谱综合实验系统,分别评价涂层抗氧化性能和红外辐射性能,并通过扫描电镜(SEM)、能谱分析(EDS)、X射线衍射仪(XRD)对涂层氧化前后的形貌与组织结构进行分析。结果钼合金Si-Cr-Ti-SiC-Mn O_2涂层在700、900℃的法向发射率分别达0.85、0.88,在1550℃高温有氧环境下的静态抗氧化寿命达7 h。原始涂层呈四层复合梯度结构,由外到内分别为SiO_2+Mn3O_4+M5Si3(M指Mo、Cr、Ti)、M5Si3+Mo Si2+SiC+Mn3O_4、Mo Si2、Mo5Si3。高温氧化后,涂层四层复合结构由外到内转变为SiO_2+(Cr,Ti)5Si3+Mn Cr2O_4+Mn3O_4、M5Si3+SiC+Mn Cr2O_4+Mn3O_4、Mo Si2、M5Si3。高温氧化过程中,MSi2高硅化物层逐渐转变为M5Si3低硅化物层,涂层表面形成含Mn Cr2O_4尖晶石相和复合硅化物的致密SiO_2玻璃膜。结论 Si-Cr-Ti-SiC-Mn O_2涂层可有效提高钼合金基体的红外辐射性能和高温抗氧化性能,复合硅化物与硅锰复杂氧化物具有良好的抗氧化性能、高辐射性能和自愈合性能。     

电弧离子镀NiAlHf涂层的抗高温氧化性能

目的通过电弧离子镀技术,获得抗氧化性能优良的NiAl涂层。方法采用电弧离子镀技术,在弧流为110 A,偏压为-50 V的参数下沉积NiAlHf涂层。通过X射线衍射仪(XRD)和扫描电子显微镜(SEM)对涂层的物相结构和形貌进行分析,通过能谱仪(EDS)分析涂层的成分。采用恒温氧化增重实验对涂层的氧化动力学进行分析。结果由电弧离子镀技术制备的NiAl涂层致密均匀,无大颗粒、孔洞等缺陷。涂层主要由β-NiAl相组成,活性元素Hf固溶在主相中。NiAlHf涂层表现出良好的抗高温氧化性能,动力学曲线符合抛物线规律,在1150℃下恒温氧化200h的平均氧化速率为0.0841g/(m^2×h),远优于传统MCrAlY涂层体系。NiAlHf涂层在氧化初期形成保护性的α-Al2O3氧化皮以及少量亚稳态的θ-Al2O3,随后θ-Al2O3逐渐转变为稳态的α-Al2O3。Hf在涂层表面富集从而形成HfO2,对氧化皮形成了钉扎作用,增强了氧化皮的粘附性,提高了涂层的抗氧化性能。随着氧化的进行,涂层中的β-NiAl相逐渐转变为γ'-Ni3Al相。结论 NiAlHf涂层在1150℃下仍具备优良的抗高温氧化性能,对下一代耐更高温度涂层开发,电弧离子镀NiAl涂层的技术推广及工业化应用有一定的指导作用。     

磁控溅射Ni_3(AlCr)微晶涂层的抗氧化性能

研究了铸态Ni3(AlCr)合金及其微晶溅射涂层在900—1000℃下的高温氧化性能,结果表明:铸态Ni3(AlCr)合金在氧化过程中,开始形成以Al2O3为主含有少量NiAl2O4的氧化膜,但氧化膜的粘附性很差,在冷却时很容易剥落,在继续氧化过程中合金表面将形成NiO膜,由于NiO的保护性较差,合金表现出“失稳氧化”行为。而溅射微晶Ni3(AlCr)涂层表面形成的氧化膜与基体粘附良好,冷却过程中未发生剥落。长时间氧化后表面氧化膜只由Al2O3和NiAl2O4组成,未出现NiO,因此溅射微晶化合金的抗氧化     

CoCrAlY表面改性后热障涂层高温氧化及热震性能

采用大气等离子喷涂技术（APS）在镍基高温合金表面制备了CoCrAlY粘结层,利用电子束蒸发镀膜在CoCrAlY表面蒸镀纳米铝膜,并使用强流脉冲电子束熔敷纳米铝膜进行表面改性,最后使用APS在表面改性后的CoCrAlY表面沉积陶瓷层制备了热障涂层.在空气环境中对热障涂层进行高温氧化试验和热震试验.结果表明,CoCrAlY表面改性后热障涂层经1 050℃静态空气氧化后,界面处生成的热生长氧化物（TGO）具有较高的连续性和致密性,有效阻碍了氧化的进一步发展且避免尖角型氧化物的形成,提高了热障涂层的抗氧化能力;在1 050℃高温加热后10℃水淬热震条件下,脱落率仅为2%左右.     

Microstructure and high-temperature friction and wear behavior of WC-(W,Cr)2C-Ni coating prepared by high velocity oxy-fuel spraying

WC-(W,Cr)₂C-Ni coating was prepared by high velocity oxy-fuel spraying (HVOF). The microstructure and phase composition of the as-sprayed coating and that after oxidation at high temperature were analyzed by means of scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The oxidation behavior of as-sprayed coating and starting powders was evaluated by thermogravimetry. Dry sliding friction and wear behavior of the WC-(W,Cr)₂C-Ni coating sliding against Si₃N₄ ball at different temperatures (room temperature 20 °C and elevated temperature of 700 °C and 800 °C) was evaluated using an oscillating friction and wear tester. Besides, the microhardness and fracture toughness of the coating was also measured. Results show that sintering agglomerated WC-20 wt.%Cr-7 wt.%Ni powder is an effective method to prepare agglomerated and sintered WC-(W,Cr)₂C-Ni composite powder. The excellent oxidation resistance of WC-(W,Cr)₂C-Ni coating is mainly resulted from a double-decker shell-core microstructure formed in the coating. The composition of the outer shell is (W,Cr)₂C phase and that of the inner shell is Cr₃C₂. During high-temperature friction and wear test, well remained hard WC phase in the WC-(W,Cr)₂C-Ni coating can guarantee its good mechanical properties and wear resistance, and newly generated nano NiWO₄, CrWO₄ and Cr₂WO₆ particles can further improve these properties significantly.     

Oxidation protection of NiCoCrAlY coatings on γ-TiAl

The effect of NiCoCrAlY overlay coatings on the oxidation resistance of γ-TiAl was studied at 900 ℃ in static air. To hinder the interdiffusion of the elements, the Al/Al2O3 layer was added between the coating and the alloy. The results show that the TiAl alloy exhibits poor oxidation resistance. NiCoCrAlY coating can not effectively protect the γ-TiAl substrate from high temperature oxidation because of the serious interdiffusion between the coating and the substrates. With Al/Al2O3 diffusion barrier, the NiCoCrAlY coating exhibits excellent oxidation protection on γ-TiAl alloy.