NiCrWMoCuCBFe涂层的制备及其力学性能研究

目的 探究NiCrWMoCuCBFe涂层的微观组织结构、物相组成及其力学性能。方法 通过霍尔流速计表征了喷涂粉末的流动性和松装密度,采用超音速火焰喷涂在316L不锈钢表面制备了NiCrWMoCuCBFe涂层,利用SEM、EDS分别对喷涂粉末的形貌、涂层的组织结构以及粉末和涂层中的元素组成进行了表征,采用XRD、Raman分析了涂层中的物相,使用显微硬度计及万能材料试验机考察涂层的硬度、结合强度和抗弯强度,并分析了涂层的断裂失效机理。结果 NiCrWMoCuCBFe喷涂粉末具有良好的流动性,在喷涂过程中没有发生严重的氧化现象。通过超音速火焰喷涂制备的NiCrWMoCuCBFe涂层具有致密的层状组织结构,其物相主要是Ni基固溶体,但是也出现了少量的NiO和Cr2O3。此外,涂层的截面硬度与表面硬度相当,约为600HV300 g,且涂层与316L不锈钢的结合强度较高,大于70 MPa。三点弯曲试验中,持续加载至载荷为1800 N,应变为(4.81±0.3)%时,涂层达到强度极限,产生明显的塑性变形;而当载荷仍然保持1800 N,应变继续增加达到(11.43±0.03)％时,涂层与316L不锈钢基材的结合界面彻底开裂失效,此时涂层内部同时具有横向裂纹和纵向裂纹,样品的抗弯强度约为(1.87±0.02) GPa。结论 超音速火焰技术制备出的NiCrWMoCuCBFe涂层具有良好的致密性及优异的力学性能。     

氧气-空气混合助燃超音速火焰喷涂WC-Co涂层性能研究

采用液体燃料氧气-空气混合助燃超音速火焰喷涂(HVO/AF)工艺在45钢表面制备WC-Co涂层,采用扫描电镜(SEM)、X射线衍射(XRD)表征了涂层的微观结构及相组成,并对涂层的孔隙率、显微硬度和结合强度进行了分析.研究结果表明,采用液体燃料氧气-空气混合助燃超音速火焰喷涂制备的涂层均具有较好的性能,超音速火焰喷涂氧气与空气混合比例对涂层的性能影响较大,采用HVO/AF喷涂技术能有效地抑制WC的氧化和分解,降低了涂层的孔隙率,提高了WC-Co涂层的硬度和结合强度等性能.涂层质量要好于传统的氧气助燃超音速火焰喷涂.     

超音速火焰喷涂WC/Co涂层的组织性能研究

分析比较了等离子喷涂、超音速火焰喷涂的WC／Co涂层的形貌、显微组织、孔隙率、硬度、结合强度及其耐磨性。结果表明：超音速火焰喷涂涂层具有与粉末相近的相结构，与等离子喷涂相比涂层具有高的致密度、硬度和良好的耐磨性，涂层与基体结合情况也得到很大的改善。     

Al2O3弥散强化316L不锈钢粉末的高速火焰喷涂

采用高能球磨工艺制备了Al2O3弥散强化316L不锈钢喷涂粉末,并进行高速火焰喷涂(HVOF)试验.研究了弥散强化粉末及其喷涂层的微观组织结构和硬度.采用销-盘磨损试验机测试了涂层的耐磨性能.结果表明,球磨加工后,Al2O3颗粒尺寸大多小于1 μm,由微米级、亚微米级及纳米级粒子组成并均匀分布在316L不锈钢基体粉末中.随着球磨时间的增加,粉末的显微硬度提高.喷涂后球磨粉末的微观组织结构基本不变,喷涂层的硬度比对应球磨粉末硬度低,其耐磨性明显优于单纯不锈钢粉末涂层.     

高速火焰与等离子喷涂WC／Co涂层的性能比较

分析比较了超音速喷涂与等离子体喷涂的ＷＣ／Ｃｏ涂层的形貌,显微组织结构,孔隙率,硬度及其耐磨性,结果表明超音速火焰喷涂的ＷＣ／Ｃｏ涂层具有与粉末相近的相结构,也说ＷＣ颗粒在超音速火焰喷涂过程中,只有极少部分被分解和氧化,同时涂层具有很高的致密度,硬度和良好的耐磨性,涂层与基体的结合情况也得到很大的改善。     

热处理对超音速火焰喷涂FeAl-Al涂层组织结构的影响

目的通过超音速火焰喷涂(High Velocity Oxygen Fuel,HVOF)的粉末喂料设计,获取结构致密的铁铝金属间化合物涂层,并详细考察热处理对所制备涂层组织结构的影响。方法在铁铝合金粉末喂料中添加质量分数为5%的铝粉,改善喷涂效果,在316L不锈钢表面制备致密的FeAl-Al涂层,并进行真空热处理。采用X射线衍射仪(XRD)、场发射扫描电子显微镜(SEM)、能谱仪(EDS)及维氏显微硬度计,详细分析了涂层在不同热处理温度下的微观组织、成分、结构与显微硬度的变化。结果喷涂态FeAl-Al涂层厚度约为150μm,物相为Fe2Al5,未检测到单质Al。随着热处理温度升高,Fe2Al5相的衍射峰逐渐增强。500℃热处理后,喷涂态涂层中扁平粒子间存在的细微孔隙大量消失,涂层致密性明显提高。但是800℃热处理后,涂层中产生了与界面平行的裂纹。喷涂态FeAl-Al涂层的硬度为465.06HV0.1,500℃热处理2 h后增加至472.06HV0.1,继续提高热处理温度,涂层的显微硬度则明显下降。结论在粉末喂料中引入质量分数为5%的Al粉,可明显改善超音速火焰喷涂效果,获得结构致密、与基体结合牢固的FeAl-Al涂层。合适的热处理能进一步消除喷涂缺陷,使涂层显微硬度增加,微观结构更加致密。     

冷喷涂Ta涂层组织及腐蚀性能

利用冷喷涂技术在316L不锈钢表面制备Ta涂层.采用X射线衍射仪(XRD)、扫描电镜(SEM)对涂层的相结构和微观组织进行了分析,通过显微硬度计和万能力学试验机测定涂层的显微硬度和结合强度;采用电化学试验机测试了涂层和不锈钢基体的腐蚀性能.结果表明:涂层微观组织均匀致密,孔隙率为0.5％;涂层与基体结合良好,结合强度为60 MPa;涂层平均显微硬度为256 HV0.3;Ta涂层的自腐蚀电位(-0.25V)略低于316L不锈钢块体(-0.13 V),自腐蚀电流密度(2.16× 10-7A/cm2)比316L不锈钢(4.83×10-7A/cm2)降低了一倍,钝化电位及钝化电流分别为-0.06 V和1.05× 10-4A/cm2,具有很宽的钝化区,能够有效保护316L基体.     

煤油流量对HVOF铁基非晶涂层组织与性能的影响

以工业原材料制备的FeCoCrMoCBY非晶粉末为喷涂材料,采用超音速火焰喷涂(HVOF)制备铁基非晶合金涂层。通过X射线衍射仪(XRD)、差示扫描热仪(DSC)、扫描电子显微镜(SEM)、维氏显微硬度计等测试方法,探讨煤油流量对涂层显微组织、微观结构及显微硬度的影响,并分析涂层与316 L不锈钢在1 mol/L HCl溶液中的动态极化特征。结果表明:涂层与基体结合良好,呈现典型的层状结构,非晶含量高,表现出比316 L不锈钢更高的耐腐蚀性能。其它参数一定时,煤油流量越高,涂层致密度越高,非晶含量先增多后减少,显微硬度先增大后减小;当氧气流量为50 m~3/L,煤油流量为26 L/h时,涂层非晶含量最高,为99.4%,孔隙率为1.51%,自腐蚀电流密度低,为5.62×10~(-6) A/cm~2,自腐蚀电位为-0.36 V,耐腐蚀性能表现最佳。     

HVOF喷涂Ni基涂层性能的研究

采用超音速火焰喷涂技术（HVOF）制备了3种镍基涂层，并对涂层的性能进行测试。结果表明：烧结粉末Ni60制备的涂层结合强度达44．6MPa、显微硬度963．8HV，均明显优于包覆粉末Ni包C、Ni包MoS2制备的涂层；Ni包C涂层孔隙率最高，达5．4％，并含有许多的未熔软质相；涂层中的镍起粘结作用，能显著提高涂层的结合强度和显微硬度；起减磨作用的MoS2和C相会明显降低涂层的结合强度。     

超音速火焰喷涂钴基陶瓷涂层的组织与性能研究

本文在氧气流量和喷涂距离一定的条件下,研究了燃气流量对超音速火焰喷涂WC-Co涂层显微组织、相结构及性能的影响。结果表明:燃气流量低的涂层结合强度、显微硬度最低,孔隙率最大;燃气流量适中的涂层结合强度最高,显微硬度低于另外两种涂层,燃气流量最高的涂层,燃气流量高的涂层的显微硬度最大。     

Properties of Fe-based Amorphous Alloy Coatings with Al2O3-13% TiO2 Deposited by Plasma Spraying

采用大气等离子喷涂技术成功在Fe普碳钢基材上制备了含有不同质量分数Al2O3-13%Ti O2颗粒的Fe基非晶复合涂层,其中Fe基非晶相成分为Fe71Cr5B4Si4Ni3Mo3W10(wt%),并对涂层的微观结构、显微硬度和耐蚀性能进行了研究。在Fe基非晶相与Al2O3-13%Ti O2陶瓷相界面观察到Fe、Ti、W、Al和O元素的互扩散现象,这种微区冶金结合减少了由于第二相的加入导致的涂层孔隙并增加了相间的结合强度。当加入的Al2O3-13%Ti O2质量分数≥16 wt%时,涂层的显微硬度升高≥20%;复合非晶涂层在10 wt%Na OH溶液中的耐腐蚀性能高于1Cr18Ni9Ti不锈钢。     

Improvement of corrosion resistance of high-velocity oxyfuel-sprayed stainless steel coatings by addition of molybdenum

To improve the marine corrosion resistance of stainless steel coatings fabricated by high-velocity oxyfuel (HVOF) spraying with a gas shroud attachment, the molybdenum (Mo) content of stainless steel was increased to form coatings with a chemical composition of Fe balance-18mass%Cr-22mass%Ni-2∼8mass%Mo. These coatings were highly dense, with <0.1 vol.% in porosity, and less oxidized, with 0.5 mass% in oxygen content at most. The corrosion mechanism and resistance of the coatings were investigated by electrochemical measurement, chemical analysis, and statistical processing. The general corrosion resistance of the coatings in 0.5 mol/dm³ sulfuric acid was improved with increases in Mo content, and the corrosion rate could be decreased to 8.8 × 10⁻² mg/cm² per hour (∼1 mm/year) at 8 mass% Mo. The pitting corrosion resistance of the coatings in artificial seawater was improved with increases in Mo content and was superior to that of the 316L stainless steel coating. The crevice corrosion resistance of the coatings in artificial seawater was improved and the number of rust spots at 4 mass% Mo was decreased to 38% of that for the 316L coating. Accordingly, Mo is highly effective in improving the corrosion resistance of the stainless steel coatings by HVOF spraying.     

活性燃烧高速燃气喷涂WC-CoCr涂层的微观组织及性能

利用活性燃烧高速燃气(AC-HVAF)喷涂技术在0Cr13Ni5Mo不锈钢表面制备了WC-CoCr涂层,并利用XRD、SEM、滑动磨损以及电化学试验分析了涂层的微观组织以及耐磨耐蚀性.结果表明,涂层具有优异的微观结构以及良好的耐磨耐蚀性.XRD分析未发现其他喷涂技术普遍存在的W2C以及W相,AC-HAVF喷涂技术可以有效抑制WC的分解;涂层致密且与基体结合良好,孔隙率仅为0.75%.滑动磨损试验表明,涂层具有很低的磨损率.其主要原因为涂层硬度极高、WC颗粒细小和没有W2C相.电化学试验表明,WC-CoCr涂层的耐蚀性优于基体0Cr13Ni5Mo不锈钢,Cr的加入、W的缺少以及孔隙率低是WC-CoCr涂层耐蚀性优异的重要原因.     

Electrochemical characteristics and interfacial contact resistance of multi-layered Ti/TiN coating for metallic bipolar-plate of polymer electrolyte membrane fuel cells

Metallic bipolar-plates have advantages over non-porous graphite ones due to their higher mechanical strength and better electrical conductivity. However, corrosion resistance and interfacial contact resistance are major concerns that remain to be solved, since metals such as stainless steels may develop oxide layers that decrease electrical conductivity, thus lowering fuel cell efficiency. In this study, multi-layered nitride coatings consisting of Ti and TiN were deposited on 316L stainless steel (SS316L) by a D.C magnetron sputtering method to enhance the corrosion resistance and to lower the interfacial contact resistance (ICR) of metallic bipolarplates for a polymer electrolyte membrane fuel cell (PEMFC). Electrochemical methods were conducted and ICRs of the coated specimens were measured to investigate the potential of the coated metallic bipolar-plate for use in PEMFCs. The multi-layered Ti/TiN coating deposited on SS316 showed lower ICR values than the single-layered TiN coating, and improved corrosion resistance when the PEMFC was not in operation while the degradation of the coating layer was observed in both cathodic and anodic working environments.     

热镀锌沉没辊的耐锌腐蚀失效过程

采用超音速火焰喷涂技术在316L不锈钢基体上制备WC-12Co涂层,并测试其在430℃锌液中的耐腐蚀性,分析沉没辊的腐蚀机理以及失效过程。采用SEM、EDS和XRD分析了腐蚀前、后涂层表面显微结构、化学成分及其相组成的变化。结果表明,WC-12Co粒子之间通过高速碰撞发生强烈的塑性变形而结合在一起,涂层内部致密性很好,喷涂过程中没发生明显氧化现象;涂层的显微硬度平均为1 215HV0.2,结合强度达到85MPa;无涂层试样在腐蚀59h后直径减少20%;经过10天的浸锌试验后,涂层开始产生均匀性腐蚀,涂层中的Co基体受液锌腐蚀生成Co5Zn21化合物,涂层开始遭到破坏;经过15天浸锌试验后,部分锌液穿过涂层与基体中的Fe化合生成FeZn13(即锌渣),涂层局部开始脱落,涂层失效开始。     

大气等离子喷涂TiB2-316L不锈钢基复合涂层及其耐磨性能

分别采用高能球磨制备了TiB2含量(质量分数)为10%的316L不锈钢基复合粉,高能球磨与喷雾干燥造粒工艺制备了TiB2含量(质量分数)为40%的316L不锈钢基复合粉,大气等离子喷涂制备相应的TiB2-316L不锈钢基金属陶瓷涂层与316L不锈钢涂层.室温下采用高速环块磨损试验研究TiB2-316L不锈钢基金属陶瓷涂层的磨损特性.采用X射线衍射分析涂层物相,扫描电镜分析喷涂粉末、涂层结构和摩擦副磨损表面形貌.结果表明,大气等离子喷涂两种制粉工艺获得的316L不锈钢基TiB2复合粉能获得较耐磨的316L不锈钢基TiB2复合涂层,耐磨性高于316L不锈钢涂层,且TiB2在复合涂层中增强涂层耐磨性的原因是TiB2颗粒在涂层316L韧性基体中充当强化相,且TiB2在摩擦接触处摩擦氧化形成的氧化产物具有自润滑特性,能减少涂层的磨损量.     

TiAlNb intermetallic compound coating prepared by high velocity oxy-fuel spraying

Ti_28.35Al_63.4Nb_8.25 (at.%) intermetallic compound coatings were sprayed onto 316 L stainless steel substrates by HVOF processes using various parameters. By varying the grit blasting pressure between 0.11 and 0.55 MPa, the effects of substrate roughness on the adhesion of TiAlNb thermal sprayed coatings were investigated. The microstructure, porosity and microhardness of the coatings were characterized by SEM, XRD, Image Analysis and Vickers hardness analysis. The tensile adhesion test (TAT) specified by ASTM C 633-79 was used to measure the tensile bonding strength of the coating. The results show that the coatings with substrate roughness of 8.33 μm displayed the best combined strength. TiAlNb coatings had a lamellar microstructure with different spraying parameters. The porosity, bonding strength, microhardness of coatings were assessed in relation to the spraying processes. The thickness of bond coat on the bond strength of coatings was also discussed.     

Electrochemical behavior of thermally sprayed stainless steel coatings in 3.4% NaCl solution

Four types of stainless steel coatings prepared by a high velocity oxy-fuel spraying system (HVOF) were studied. Differences among coated steels were related to the spraying parameters, which influenced the behavior of the samples against the corrosion. The electrochemical behavior of the stainless steel coatings was strongly influenced by porosity, the presence of micro- and macro-cracks, and also of un-melted particles. Once the electrolyte reached the steel substrate via these defects, the galvanic pair formed between the coating and substrate-accelerated corrosion, leading to the depletion of the coating.     

Corrosion behaviors of arc spraying single and double layer coatings in simulated Dagang soil solution

Three kinds of single layer coatings of Zn, Zn15Al, 316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L stainless steel by arc spraying were developed to protect the metal ends of prestressed high-strength concrete (PHC) pipe piles against soil corrosion. The corrosion behaviors of the coated Q235 steel samples in the simulated Dagang soil solution were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and natural immersion tests. The results show that the corrosion of the matrix Q235 steel is effectively inhibited by Zn, Zn15Al, Zn+316L and Zn15Al+316L coatings. The corrosion rate value of Zn15Al coated samples is negative. The corrosion products on Zn and Zn15Al coated samples are compact and firm. The corrosion resistance indexes of both Zn and Zn15Al coated samples are improved significantly with corrosion time, and the latter are more outstanding than the former. But the corrosion resistance of 316L coated samples is decreased quickly with the increase in immersion time. When the coatings are sealed with epoxy resin, the corrosion resistance of the coatings will be enhanced significantly.