感应重熔TiC增强Fe-Al金属间化合物复合涂层的显微组织研究

采用Fe粉、Al粉及TiC硬质颗粒等的混合粉料,利用火焰喷涂加感应重熔的方法得到TiC增强Fe-Al金属间化合物复合涂层,涂层中TiC颗粒含量为15%(质量分数)。用X射线衍射仪(XRD)测定复合涂层的物相组成。用扫描电子显微镜(SEM)观察复合涂层的微观形貌,涂层中出现了TiC增强Fe-Al金属间化合物区,TiC硬质颗粒在Fe-Al金属间化合物中呈白色点状分布。用维氏硬度计测得复合涂层的显微硬度为540.4MPa。     

碳化钛掺杂的铁基复合涂层的制备及其耐磨性能研究

采用“ 喷雾造粒 + 等离子球化” 复合工艺, 成功制备了环境友好且价格低廉的 TiC/316L 复合粉末, 并 采用超音速火焰喷涂工艺沉积了复合涂层。 利用扫描电镜、 维氏硬度计、 往复式摩擦磨损仪表征了该复合粉末 及涂层的微观结构、 力学性能及耐磨性能。 结果表明, 新工艺制备的 TiC/316L 金属陶瓷复合粉末具有高球形 度、 高致密及陶瓷相分布均匀的特点, 可直接应用于热喷涂。 TiC/316L 复合涂层的孔隙率为 0.75%, 硬度为 860 HV0.3, 磨损率为 5× 10-5 mm3N-1m-1; 相比于 316 L 不锈钢涂层, 上述指标均大幅提升。 其原因在于： (1) TiC 掺杂 改善了铁基粉末的熔化程度, 大幅提升粉末的扁平化率; (2) TiC 陶瓷相沉积时表现出喷丸效应, 进一步致密化 涂层; (3) TiC 掺杂抑制了复合涂层的层状剥落。     

大气和低压等离子喷涂ZrO2-8%Y2O3涂层及性能研究

本研究采用大气等离子(APS)和低压等离子喷涂(LPPS)两种方法分别对成分为ZrO2-8%Y2O3的微粉球形造粒-烧结粉末(Spherical Spray Dried Sintered:SSS)和微粉粘接-破碎粉末(Mucilage Adhered Crushed:MAC)进行了喷涂实验。使用金相显微镜,X-Ray及维氏硬度仪等,分析了涂层的微观组织,相结构及硬度。结果表明,APS喷涂SSS粉末制备的涂层为多孔结构,气孔率高于20%,LPPS喷涂SSS粉末制备的涂层呈现纵向生长趋势。而对于MAC粉末,两种方法制备的涂层孔隙率明显低于SSS粉末制备的涂层,其中LPPS喷涂MAC粉末制备涂层的致密性和硬度更高。两种方法喷涂SSS粉末,涂层相组成与粉末相同,粉末与涂层中只含有T相,而APS和LPPS喷涂MAC粉末,涂层中出现了m相。     

氩弧熔覆TiB/FeB增强Fe基复合涂层组织与性能研究

以Fe粉、Ti粉和B粉为原料,利用氩弧熔覆技术在Q235钢基材表面制备出TiB/FeB增强Fe基复合涂层,应用SEM和XRD方法分析了涂层的显微组织.并测试了涂层的硬度和耐磨性.结果分析表明:在Q235钢表面成功制备了以α-Fe为基体,以TiB/FeB颗粒为增强相的复合涂层.性能分析结果表明:涂层的显微硬度可达1 100HV,涂层耐磨性较基体提高近12倍.复合涂层的磨损机理为显微擦伤式磨损.     

氩弧熔敷原位自生TiC／Ni60A复合涂层的滑动磨损特性

利用氩弧熔敷技术,以Ni60A自熔合金粉、钛粉和石墨粉为原料,在16Mn钢表面原位合成了TiC增强Ni基复合材料涂层以提高基体的耐磨性.借助扫描电镜、X射线衍射仪、显微硬度计对复合涂层的组织和性能进行了分析.结果表明:熔敷层与基体呈冶金结合,无裂纹、气孔等缺陷,TiC颗粒弥散分布于熔敷层中;复合涂层有很高的硬度,在室温干滑动磨损试验条件下具有优异的耐磨性能并随着(Ti C)含量的增加而提高.     

不同热处理条件下Fe非晶涂层组织和硬度变化

用Fe基非晶粉末作为喷涂材料,利用一种新型的活性燃烧高速燃气喷涂技术(AC-HVAF)在0Cr13Ni5Mo不锈钢上制备了一种高非晶含量的Fe基非晶涂层,采用不同的热处理工艺来使喷涂的非晶涂层晶化,利用DSC分析来测定热处理后涂层中非晶和结晶形成的纳米晶之间的比例,用XRD观察涂层的晶体结构,场发射扫描电镜观察热处理后涂层的晶化状态,显微硬度仪测试涂层的显微硬度。试验结果表明:随着温度的升高涂层的晶化程度不断的增加,析出尺寸约为二十几纳米左右的纳米晶组织。在600～610℃热处理时,涂层晶化析出Cr_(15.58)Fe_(7.42)C_6相和Fe_7C_3相,而在615～630℃时,则主要为Fe_(23)(C,B)6相、Fe_(23)B_6相、Fe_(-)Cr相和原有的Fe_7C_3相。而随着温度的升高,涂层的显微硬度呈非线性的变化趋势。     

原位自生TiB+TiC增强Ti-Fe基复合材料微观组织和力学性能研究

以Ti粉、Fe粉和B_4C粉末为原料,采用冷等静压+高真空烧结方法制备了不同(TiB+TiC)增强相体积分数的Ti-Fe合金基复合材料(Fe元素质量分数为5%～15%),重点讨论了Fe含量和增强相对复合材料微观组织和力学性能的影响规律。结果表明,在1 150～1 250℃烧结温度下制备出Ti-Fe合金基复合材料致密度随Fe含量与增强相体积分数升高而降低。Fe含量增加使基体中α相层片状结构细化,而B_4C粉末的添加生成原位自生TiC颗粒和TiB纤维增强相,基体结构由层片状转变为等轴状。材料力学性能随Fe含量和增强相体积分数增加而提高。在1 150℃烧结制备的Ti-15%Fe-10vol%(TiB+TiC)复合材料硬度(HV)达到334,抗压强度达到2 040 MPa。     

超音速火焰喷涂铁基非晶纳米晶涂层微观组织及性能的研究

利用先进的AC-HAVF喷涂技术制备了Fe基非晶纳米晶涂层,研究了其微观组织、热稳定性以及耐磨耐蚀性能.试验结果表明涂层主要由FeNi3和Fe2B相组成;涂层与基体结合很好,涂层的孔隙率约为1.8%;涂层表面硬度分布不是均匀,最高可达1 570 HV,平均硬度为1361.1 HV;涂层具有优异的耐磨耐蚀性,其磨损体积是0Gr13Ni5Mo不锈钢的0.15倍,平均腐蚀速度是0Cr13Ni5Mo不锈钢的0.56倍,涂层的磨损机理主要是疲劳磨损;所获得的非晶纳米晶涂层有很好的热稳定性.     

工艺参数对超音速火焰喷涂Fe基非晶涂层性能的影响

Fe基非晶涂层具有优异的耐磨、耐蚀性能,以及较高的性价比,适合在表面防护涂层领域广泛应用。本文通过正交试验研究了煤油流量、氧气流量、送粉速率、喷涂距离对超音速火焰喷涂制备的Fe基非晶涂层的孔隙率、硬度、耐磨性能的影响。采用图像法、显微硬度计和摩擦磨损试验机分别对Fe基非晶涂层的孔隙率、硬度、耐磨性能进行了表征。采用X射线衍射仪和扫描电镜分别对涂层的相组成和显微结构进行了表征。通过极差分析法分析得出以涂层孔隙率最低为目标的优化制备工艺,最佳喷涂工艺参数为:煤油流量0.41 L/min,氧气流量830 L/min,喷涂距离430 mm,送粉速率40 g/min。结果表明:送粉速率和氧气流量对涂层孔隙率影响较大,进而影响涂层的硬度及耐磨性能。孔隙率随着氧气流量和送粉速率的增加而增加,随着煤油流量和喷涂距离的增加而降低。制备的Fe基非晶涂层硬度达到1158.9HV0.2,孔隙率为1.22%,磨损实验的质量损失量只有316L不锈钢的一半。     

电弧喷涂含陶瓷颗粒铝基复合涂层的微结构和性能

采用5052半硬铝带分别包覆Al_2O_3、SiC、B_4C、TiC陶瓷颗粒制备的粉芯丝材进行电弧喷涂试验,制备了含陶瓷颗粒的铝基复合涂层。利用光学显微镜、XRD分析了涂层的微观组织和相结构,测试了复合涂层的显微硬度、耐磨性及耐腐蚀性。研究结果表明,制备的铝基复合涂层中含有一定数量的未熔陶瓷颗粒,涂层较为致密,无明显缺陷。含陶瓷铝基涂层的物相主要由Al和所添加的陶瓷相构成,其中在含B_4C陶瓷涂层中还存在Al_3BC、Al_4C_3和AlB_2等新相。陶瓷颗粒的加入有利于提高铝基复合涂层的显微硬度,其中B_4C的加入使涂层中基体相显微硬度提高了1.5倍,这是由于B_4C陶瓷和Al反应生成Al_3BC、Al_4C_3和AlB_2硬质相。复合涂层的耐磨性均优于纯铝涂层,摩擦磨损的形式主要为粘着磨损。动电位极化腐蚀试验表明,含SiC和TiC陶瓷涂层具有较低的腐蚀电流,耐蚀性较好,含SiC陶瓷的复合涂层出现了明显的钝化现象。     

Fabrication of TiC/Fe–Ni cermet coatings by reactive thermal spraying of Fe–Ti–Ni–C composite powder

Abstract

A mixture of ferrotitanium, nickel powders and sucrose was heated with an intention of carbonising the sucrose. The tiny ferrotitanium, nickel particles are bound by the carbon obtained from pyrolysis of the sucrose to form a unique structure of Fe–Ti–Ni–C composite powder for reactive thermal spraying. The carbon is a reactive constituent as well as the binder in the composite powder. TiC/Fe–Ni cermet coating was prepared by reactive plasma spraying of this powder. A mass of TiC particles were in situ synthesised and uniformly distributed in the Fe–Ni alloy matrix without residuals of raw materials in the coating. The coating is consisted of two different areas: one is the composite area, where lots of spherical fine TiC particles (100–500 nm) are homogeneously distributed within the Fe–Ni alloy matrix; the other is a small fraction of TiC accumulation. The volume fraction of composite area is >87%.     

等离子喷涂制备铁基复合陶瓷涂层的研究

以铝粉和氧化铁粉作原料,采用等离子反应合成技术制备出了金属颗粒增韧的FeAl2O4-Al2O3-Fe复合陶瓷涂层。研究分析了复合涂层的组织及其性能。结果表明：等离子反应合成得到了以层状基体相FeAl2O4与硬质相Al2O3为骨架,球状Fe相弥散分布于基体相上的复合涂层。复合涂层的断裂韧性和结合强度明显优于普通Al2O3涂层,特别是复合涂层的具有较高的耐磨性能。     

WC-10Co-4Cr 含量对HVOF 制备WC-10Co-4Cr/Ni60涂层性能的影响

为改善农业机械工作部件的耐磨性和耐腐蚀性能,提高其使用寿命,采用超音速火焰喷涂的技术,在45 # 钢表面制备WC-10Co-4Cr/Ni60 涂层。在Ni60 粉末中分别添加质量分数为0、10 %、20 % 和30 % 的WC-10Co- 4Cr 粉末,探究WC-10Co-4Cr 含量对WC-10Co-4Cr/Ni60 涂层性能的影响。结果表明,制备的WC-10Co-4Cr/ Ni60 涂层组织均匀致密,涂层主要由γ ( NiCr ) 相和WC 相组成,含有少量的W2C、Ni3Fe 和Cr3Si 相,没有明显 的氧化脱碳现象。30 %WC-10Co-4Cr/Ni60 涂层的硬度达到9.35 GPa,是Ni60 涂层的1.23 倍,该涂层的耐磨性能最好, 在摩擦115 m 后,单位面积的总磨损量47.2 mg/cm2,比Ni60 涂层减少了35.3 %。20 %WC-10Co-4Cr/Ni60 涂层 的断裂韧性最高为6.04 MPa·m1/2,相较于Ni60 涂层提高了24.3 %,此外,该涂层在酸性环境中的耐腐蚀性能均 最佳。     

硼化钼基涂层的制备及耐磨抗蚀性能研究

针对连续热镀锌生产线中沉没辊、 轴套等零部件的腐蚀磨损问题, 采用造粒烧结制备了 MoB-Al2O3(MA) 复合陶瓷粉末 , 采用等离子喷涂工艺制备了 MA 复合陶瓷涂层, 测试了涂层的显微组织、 显微硬度及耐熔融锌液 腐蚀磨损性能。 结果表明, 涂层显微组织均匀, 显微硬度约 1300HV100。 采用细粒度粉末、 粘结底层和封孔工艺 制备的 MA 涂层具有更好的抗腐蚀磨损能力, 经腐蚀磨损试验后涂层保持完整, 没有发生明显的腐蚀磨损。     

Wear Resistance and Bond Strength of Plasma Sprayed Fe/Mo Amorphous Coatings

Fe-based and Fe/Mo composite amorphous coatings were deposited on the surface of plain carbon steel substrates by atmospheric plasma spraying （APS）. With increasing the Mo alloy content, the microstructure of the coatings revealed more dense structure. The porosities of composite coating were all less than those of Fe-based coat- ing due to Mo alloy self-bonding performance. The ML10 friction and wear tester was employed to investigate the wear behaviors of the coatings under dry sliding conditions. It was found that the mass loss of the resultant coatings decreased with increasing Mo-based powders into the feedstock. This was attributed to the reduction of the delamina- tions resulting from improved intersplat bond with Mo addition.     

Correlation of microstructure and wear resistance of ferrous coatings fabricated by atmospheric plasma spraying

The correlation of microstructure and wear resistance in ferrous coatings applicable to diesel engine cylinder bores was investigated in this study. Seven kinds of ferrous spray powders, two of which were stainless steel powders and the others blend powders of ferrous powders mixed with Al₂O₃-ZrO₂ powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the ferrous coatings showed that various Fe oxides such as FeO, Fe₂O₃, and γ-Fe₂O₃ were formed in the martensitic (or austenitic) matrix as a result of the reaction with oxygen in air. The blend coatings containing γ-Al₂O₃ and t-ZrO₂ oxides, which were formed as Al₂O₃-ZrO₂ powders, were rapidly solidified during plasma spraying. The wear test results revealed that the blend coatings showed better wear resistance than the ferrous coatings because they contained a number of hard Al₂O₃-ZrO₂ oxides. However, delamination occurred when cracks initiated at matrix/oxide interfaces and propagated parallel to the worn surface in the case of the large hardness difference between the matrix and oxide. The wear rate of the coating fabricated with STS316 powders was slightly higher than other coatings, but the wear rate of the counterpart material was very low because of the smaller matrix/oxide hardness difference due to the presence of many Fe oxides. In order to reduce the wear of both the coating and its counterpart material, the matrix/oxide hardness difference should be minimized, and the hardness of the coating should be increased over a certain level by forming an appropriate amount of oxides.     

反应等离子喷涂TiN复相涂层的组织与性能研究

采用工业纯钛粉,利用反应等离子喷涂技术,在45钢表面原位合成TiN复相涂层。利用X射线衍射仪分析了涂层的物相组成,采用扫描电镜观察涂层的组织结构、显微压痕、断口和磨损形貌,采用能谱仪分析压痕微区成分,测试了涂层的显微硬度和耐磨性能。结果表明:复相涂层由TiN、TiN0.3、Ti3O组成;涂层具有典型的层状组织结构,且层与层之间、层与基体之间结合较好;涂层的显微硬度为983~1 254 HV0.1;显微压痕形状清晰、规则,且压痕周围无翘边现象;断口形貌说明涂层具有一定的韧性,为介于陶瓷材料与韧性材料之间的混合断裂机制;涂层在低载荷时耐磨性能最佳。     

Effect of Electron-Beam Treatment on Wear-Resistant Coatings Applied by Electroexplosive Sputtering

TiC–Mo, TiC–Ni, TiB₂–Mo, and TiB₂–Ni coatings applied to the surface of Hardox 450 steel by electroexplosive sputtering are subjected to electron-beam treatment, After electroexplosive application, the surface relief of the coatings includes features such as deformed solidifying microglobules, buildup, microcraters, microcracks, and peeling. After electron-beam treatment, the microglobules, buildup, microcraters, and microcracks disappear from the coating surface. A polycrystalline structure containing cellular elements is formed. After electron-beam treatment, the surface roughness is 1.1–1.2 μm. The thickness of the layers modified by the electron beam in the electroexplosive coatings depends linearly on the surface energy density. The greatest coating thickness is observed when using the TiB₂–Mo system; the coating thickness is least for the TiC–Ni system. That may be attributed to the thermophysical properties of the coatings. The following substructures are observed in the coatings: cellular, striated, fragmented, and subgranular. Grains with chaotically distributed dislocations and reticular dislocations are also observed. Electron-beam treatment leads to the formation of composite filled structure over the whole cross section of the remelted layer. The structure formed in this layer is more disperse and uniform than in coatings formed without electron-beam treatment. The inclusions of titanium carbide or titanium diboride in the molybdenum or nickel matrix are 2–4 times smaller than immediately after electroexplosive sputtering. Within the molybdenum or nickel grains and at their boundaries, rounded particles of secondary phase (titanium carbide or titanium diboride) are observed. They may be divided into two classes by size: particles of the initial powder (80–150 nm) that have not dissolved on irradiation; and particles formed on solidification of the melt (10–15 nm). In the electroexplosive powder coatings, the structure is mainly formed by dynamic rotation of the sprayed particles, which form a vertical structure both in the coating and in the upper layers of the substrate. The coatings have excellent operational properties: nano- and microhardness, elastic modulus of the first kind, and wear resistance in dry slipping friction.     

Correlation of microstructure with hardness and wear resistance in (TiC,SiC)/stainless steel surface composites fabricated by high-energy electron-beam irradiation

Stainless-steel-based surface composites reinforced with TiC and SiC carbides were fabricated by high-energy electron beam irradiation. Four types of powder/flux mixtures, i.e., TiC, (Ti + C), SiC, and (Ti + SiC) powders with 40 wt. pct of CaF₂ flux, were deposited evenly on an AISI 304 stainless steel substrate, which was then irradiated with an electron beam. TiC agglomerates and pores were found in the surface composite layer fabricated with TiC powders because of insufficient melting of TiC powders. In the composite layer fabricated with Ti and C powders having lower melting points than TiC powders, a number of primary TiC carbides were precipitated while very few TiC agglomerates or pores were formed. This indicated that more effective TiC precipitation was obtained from the melting of Ti and C powders than of TiC powders. A large amount of precipitates such as TiC and Cr₇C₃ improved the hardness, high-temperature hardness, and wear resistance of the surface composite layer two to three times greater than that of the stainless steel substrate. In particular, the surface composite fabricated with SiC powders had the highest volume fraction of Cr₇C₃ distributed along solidification cell boundaries, and thus showed the best hardness, high-temperature hardness, and wear resistance.     

Correlation of microstructure with hardness and wear resistance in (TiC,SiC)/stainless steel surface composites fabricated by high-energy electron-beam irradiation

Stainless-steel-based surface composites reinforced with TiC and SiC carbides were fabricated by high-energy electron beam irradiation. Four types of powder/flux mixtures, i.e., TiC, (Ti+C), SiC, and (Ti+SiC) powders with 40 wt. pct of CaF₂ flux, were deposited evenly on an AISI 304 stainless steel substrate, which was then irradiated with an electron beam. TiC agglomerates and pores were found in the surface composite layer fabricated with TiC powders because of insufficient melting of TiC powders. In the composite layer fabricated with Ti and C powders having lower melting points than TiC powders, a number of primary TiC carbides were precipitated while very few TiC agglomerates or pores were formed. This indicated that more effective TiC precipitation was obtained from the melting of Ti and C powders than of TiC powders. A large amount of precipitates such as TiC and Cr₇C₃ improved the hardness, high-temperature hardness, and wear resistance of the surface composite layer two to three times greater than that of the stainless steel substrate. In particular, the surface composite fabricated with SiC powders had the highest volume fraction of Cr₇C₃ distributed along solidification cell boundaries, and thus showed the best hardness, high-temperature hardness, and wear resistance.