激光重熔对火焰喷涂CrFeAlTi涂层组织与性能的影响

利用火焰喷涂技术在中国低活化马氏体(CLAM)钢表面制备了CrFeAlTi涂层,然后通过5 kW横流CO_2激光器对该涂层进行多道搭接重熔处理。分别采用体视显微镜、扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机以及基体拉伸试验等分析测试手段对重熔前后涂层显微组织、物相组成、显微硬度、耐磨性能以及界面结合强度进行了研究。试验结果表明:激光重熔处理消除了火焰喷涂CrFeAlTi涂层的层状组织结构、孔洞、裂纹等缺陷,使涂层表面光滑、平整,内部组织致密、均匀,与基体形成了良好的冶金结合界面。火焰喷涂涂层表层物相主要为Al_2O_3、TiO、CrO_(0.87)、AlFeO_3、Cr_3C_2和Fe-Cr,激光重熔后涂层表层主要物相为Al_2O_3、TiO_2、(Al_(0.948)Cr_(0.052))_2O_3和Cr_7C_3。激光重熔涂层的平均硬度约为1864.2 HV0.2,比火焰喷涂涂层提高了约1倍。激光重熔涂层在室温干滑动摩擦条件下的耐磨性能明显优于火焰喷涂涂层与基体CLAM钢。激光重熔后涂层与基体的界面结合强度显著提高。     

瓦楞辊表面喷涂硬质涂层耐磨性研究

利用等离子喷涂技术在瓦楞辊材料42CrMo合金钢表面喷涂Cr_3C_2-NiCr、Cr_2O_3两种硬质涂层.测试了涂层的硬度、耐磨性,并用扫描电镜(SEM)分析了两种涂层的截面、表面形貌和厚度.结果表明:等离子喷涂Cr_3C_2-NiCr涂层后试样表面硬度达到923.6HV,而喷涂Cr_2O_3涂层后试样表面硬度达到1184.1 HV.两种涂层均与基体结合紧密,有效减小了试样表面的摩擦系数,耐磨损性能也显著提高.     

超音速火焰喷涂Al-Cu-Cr准晶涂层表面不粘性和耐磨性的研究

以普通45#钢为基体,分别以FeAl晶体粉末和Al_(65)Cu_(20)Cr_(15)准晶粉末为热喷涂材料,采用超音速火焰喷涂(HVOF)方法制备涂层.使用金相显微镜和接触角测量仪分别对两种涂层的扁平粒子形态和表面润湿性进行表征,利用X射线衍射仪对准晶涂层的相结构进行分析.分别使用MH-6维氏硬度仪和MMW-1立式万能摩擦磨损试验机测量涂层的显微硬度HV和摩擦系数及磨损失重.结果表明:喷涂准晶涂层与原始粉末的相组成基本相同,都包括主相二十面体准晶I-Al_(65)Cu_(24)Cr_(11),和另外3种含量极少的晶体相,即θ-Al_(13)Cr_2(即Al_(83)Cu_4Cr_(13))、α-Al_(69)Cu_(18)Cr_(13)和ε-Al_2Cu_3;但是与原始准晶粉末相比,HVOF涂层中准晶相I-Al_(65)Cu_(24)Cr_(11)的体积含量相对减少,而另外3种晶体相含量相对增加.相同试验条件下,同FeAl为代表的常规金属晶体涂层相比,超音速火焰喷涂Al-Cu-Cr准晶涂层具有更低的摩擦系数和磨损量,而且对蒸馏水具有更大的接触角,这说明后者的减摩耐磨性能和对蒸馏水的不粘性优于前者.     

Co-28Mo-8Cr-2Si涂层在去离子水和人工海水中的气蚀性能

服役于海洋中的多种零部件往往因腐蚀-气蚀联合作用而严重损坏。文中采用超音速火焰喷涂(HVOF)技术制备了Co-28Mo-8Cr-2Si涂层,使用光学显微镜、X射线衍射仪、显微硬度计等设备分析涂层的组织结构和力学性能,使用电化学工作站考察涂层的腐蚀性能,使用超声波振动气蚀试验机评价了涂层分别在去离子水和人工海水中的气蚀性能,利用扫描电镜(SEM)观察涂层腐蚀和气蚀后的形貌。结果表明:在去离水中,涂层的气蚀机理主要是孔隙周围的扁平粒子大片剥落,气蚀6h后,涂层的累积体积损失高达4.15mm3;在人工海水中,腐蚀产物有效地填充了涂层表面的孔隙,大大降低了扁平粒子剥落情况的发生,气蚀6h后,涂层的累积体积损失仅为1.83mm3。     

Al2O3对等离子喷涂Cr2O3/TiO2/Al2O3/SiO2复合陶瓷涂层性能影响研究

目的研究Al_2O_3添加量对Cr_2O_3/TiO_2/Al_2O_3/SiO_2四元复合陶瓷涂层性能的影响。方法采用等离子喷涂技术在油气管道X80管线钢基体表面制备出具有不同Al_2O_3含量的四元复合陶瓷涂层。另外,为探究基体温度对涂层性能的影响,所有涂层均在等离子喷枪预热及室温的两种基体上制备。所制涂层的气孔率、硬度、结合力及电化学腐蚀性能分别采用煮沸称重法、维氏硬度计、划痕仪、电化学工作站进行检测,并用X射线衍射仪(XRD)、扫描电镜(SEM)分析不同Al_2O_3含量涂层的物相组成和形貌特征,研究Al_2O_3含量对涂层各性能的影响。结果随着Al_2O_3含量的增加,Cr_2O_3/TiO_2/Al_2O_3/SiO_2四元复合陶瓷涂层的气孔率呈现先降低后增加的趋势,相对应的四元复合陶瓷涂层的结合力、维氏硬度则先增加后降低。当Al_2O_3质量分数为60%时,四元复合陶瓷涂层的性能最优,气孔率为3.6%,硬度为824.6HV,结合力为53.8N。电化学腐蚀测试表明,Al_2O_3能增强涂层的耐腐蚀性能,Al_2O_3质量分数为60%时,涂层自腐蚀电位最高,为-0.28 V。另外,在基体预热和不预热条件下,所制涂层性能随Al_2O_3含量的变化一致,但是基体预热比不预热更有利于涂层性能的提高。结论 Al_2O_3的添加不仅能够有效降低涂层Cr含量,还能显著提升四元复合陶瓷涂层的各项性能,特别是耐腐蚀性。此外,等离子喷涂前对基体进行预热,有利于涂层性能提高。     

三种航空发动机供油系统典型部件的气蚀

为了研究航空发动机供油系统部件的气蚀失效机制与规律,分析了航空发动机供油系统中三种典型合金(TC6钛合金、ZL101铝合金、2Cr3WMoV钢)部件的气蚀原因,并比较了其气蚀特点.研究表明,在航空煤油介质中,材料强度和微观组织对气蚀破坏的微观行为有较大影响.三种合金中都广泛存在气蚀的相选择性行为,即那些较软易变形的或韧性较差的相通常较另一相优先被气蚀,使材料表面的整体强度下降,从而导致材料破坏的加剧.另外在航空发动机供油系统中冲蚀常伴随气蚀同时发生,常见的气蚀损伤多为"冲蚀-气蚀"复合机制所致.     

汽车发动机用AZ91合金表面喷涂与性能研究

采用等离子喷涂和激光重熔法在汽车发动机用AZ91合金表面制备了不同涂层,对比研究了涂层表面和横截面形貌、物相组成、显微硬度和电化学性能。结果表明,等离子喷涂层物相为:γ-Ni、FeNi_3、Ni_3B、WC、W_2C和Cr_7B_3,激光重熔层物相为γ-Ni、CrB、Ni_4B_3、WC、Cr_(23_B6和Cr_2B_3;显微硬度由高到低依次为:激光重熔层等离子喷涂层Ni/Al过渡层AZ91合金基材;等离子喷涂层和激光重熔层的耐腐蚀性能均高于AZ91合金基材,且激光重熔层的耐腐蚀性高于等离子喷涂层。     

高能高速等离子喷涂NiCoCrAlY涂层抗燃气热腐蚀性能

目的研究NiCoCrAlY涂层抗高温燃气热腐蚀性能。方法采用高能高速等离子喷涂工艺在Ni_3Al基高温合金IC6基体表面制备NiCoCrAlY涂层,测试了涂层与基体间的结合强度以及涂层和IC6基体在900℃高温环境下的抗燃气热腐蚀动力学曲线。并借助扫描电子显微镜和X射线衍射仪分析燃气热腐蚀试验前后涂层的显微组织和物相结构组成。结果高能高速等离子喷涂工艺制备的NiCoCrAlY涂层致密性高,孔隙率≤3%;涂层与基体结合状态好,平均结合强度达到62 MPa;涂层中氧化物和夹杂含量少。经100 h燃气热腐蚀后,基体和涂层的腐蚀速率分别为8.09 g/(m2·h)和0.50 g/(m~2·h)。结论 NiCoCrAlY涂层显著提高了IC6合金的抗燃气热腐蚀性能。涂层表面生成了以Al_2O_3和Cr_2O_3为主要成分的完整致密的氧化膜,Al_2O_3抗氧化性能好,Cr_2O_3抗腐蚀性能好,在两者共同作用下,腐蚀气氛向涂层内部的侵蚀被有效地阻挡或延缓;同时涂层内孔隙、氧化物夹杂等缺陷含量少,腐蚀气氛的扩散通道被阻隔或延长,降低了腐蚀速率,使得涂层对基体合金起到了很好的保护作用。     

纳米Fe-Al/Cr_3C_2复合涂层的制备及性能研究

目的制备纳米Fe-Al/Cr_3C_2复合涂层并对比分析结合强度、显微硬度、孔隙率,为利用热喷涂技术治理易损部件提供有效手段。方法运用自主研发的造粒系统,成功对高活性的纳米Fe-Al/Cr_3C_2复合喷涂粉体实施团聚造粒。使用高速火焰喷涂方法,在结构材料表面制备出了纳米Fe-Al/Cr_3C_2复合涂层。测试了纳米Fe-Al/Cr_3C_2复合涂层的基本性能,包括结合强度、显微硬度、孔隙率。结果纳米Fe-Al/Cr_3C_2复合喷涂材料的粒径由原始的50 nm团聚到最终的114~178μm,团聚后的纳米颗粒呈圆形或椭圆形,各成分比例保持原始比例,团聚颗粒内部仍然保持纳米粉体状态。纳米Fe-Al/Cr_3C_2表面及截面元素分布均匀、致密,纳米涂层的孔隙率、硬度和结合强度分别是微米涂层的0.25倍、1.39倍和2.43倍。结论团聚后的纳米Fe-Al/Cr_3C_2颗粒满足热喷涂材料的相关要求,纳米Fe-Al/Cr_3C_2比微米涂层具有更精细的涂层结构和更优异的基本性能。     

HVOF喷涂WC-12Co涂层性能及磨蚀机理

为提高水力机械表面抗磨蚀性能,采用超音速火焰喷涂(HVOF)喷涂微米粉末制备WC-12Co涂层,测试了涂层的显微硬度、孔隙率、结合强度及抗磨蚀性能。利用XRD表征了涂层的物相组成,并利用SEM分析了涂层的微观组织结构及磨蚀后的表面形貌,探讨了涂层在含沙水流中的磨蚀机理。结果表明,获得的WC-12Co涂层的孔隙率为0.83%,平均显微硬度达1189.7HV0.2,结合强度大于62MPa,其耐磨蚀性能是基体的3倍以上,有效提高基体的耐磨蚀性能。在含沙水流中的磨蚀主要是由沙粒冲蚀和气体气蚀所引起的。     

抗气蚀聚氨酯涂层的研究进展

随着水轮机和螺旋桨等过流件的尺寸和转速不断提高,气蚀损坏问题更加突出,因此易施工涂覆且便于设计调控的聚氨酯涂层始终是耐气蚀领域的研究热点。系统回顾了聚氨酯材料在气蚀防护领域的研究发展历程,深刻指出了这类材料作为耐气蚀涂层使用时存在的突出问题,例如耐水性、附着力、机械性能、耐磨性能和防污能力等较差,系统分析了这些因素导致涂层损坏失效的机理。针对上述问题,重点根据聚氨酯独特的分子结构,分别从表面能、电负性、化学键合、接枝改性、添加功能填料等方面,提出了改善聚氨酯涂层在复杂工况下应用性的解决办法。最后,鉴于我国对能够在海洋等苛刻环境中长期稳定服役的高性能气蚀防护涂层的急迫需求,对发展以自愈合聚氨酯为代表的集防污抗气蚀耐磨损自修复等功能于一体的新型聚氨酯材料进行了展望。     

铅黄铜合金在不同液体介质中的超声空蚀行为及机理

目的探讨铅黄铜合金在不同液体介质中的超声空蚀行为及机理。方法利用超声波振动空蚀装置,分别研究铅黄铜材料在去离子水、自来水以及3.5%NaCl溶液中的超声空蚀行为,借助金相显微镜、体视显微镜、扫描电子显微镜以及显微硬度计检测空蚀后的材料表面参数。结果经过300 min空蚀作用后,铅黄铜试样在自来水中的累计质量损失最大,在3.5%NaCl溶液中的累计质量损失最小,在去离子水中的累计质量损失居中。铅黄铜在去离子水和自来水中空蚀初期主要表现为大量的塑性变形,裂纹在晶界处萌生并沿横向和纵向不断扩展,蚀坑细小且形状不规则。在3.5%NaCl溶液中,铅黄铜空蚀初期的塑性变形和裂纹发展不明显,但有明显的选择性空蚀倾向,蚀坑形状以唇状为主,蚀坑口径更大,深度更深。铅黄铜在3种液体介质中空蚀后都产生了几百微米的加工硬化层,其中,在3.5%NaCl溶液中空蚀后的硬化层最厚,最大硬度值增幅达13.6%。随着空蚀时间的延长,材料近表层逐渐软化。结论铅黄铜在3种液体介质中的抗空蚀性能高低顺序为3.5%NaCl溶液去离子水自来水。     

Alternative Gas Mixtures in Arc Spraying: A Chance to Improve Coating Properties and Residual Stress States

The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young’s moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.     

Structure and cavitation erosion behavior of HVOF sprayed multi-dimensional WC–10Co4Cr coating

A new kind of multi-dimensional WC–10Co4Cr coating which is composed of nano, submicron, micron WC grains and CoCr alloy, was developed by high velocity oxy-fuel (HVOF) spraying. Porosity, microhardness, fracture toughness and cavitation erosion resistance of the multi-dimensional coating were investigated in comparison with the bimodal and nanostructured WC–10Co4Cr coatings. Moreover, the cavitation erosion behavior and mechanism of the multi-dimensional coating were explored. Results show that HVOF sprayed multi-dimensional WC–10Co4Cr coating possesses low porosity (≤0.32%) and high fracture toughness without obvious nano WC decarburization during spraying. Furthermore, it is discovered that the multi-dimensional WC–10Co4Cr coating exhibits the best cavitation erosion resistance which is enhanced by approximately 28% and 34%, respectively, compared with the nanostructured and bimodal coatings in fresh water. The superior cavitation resistance of multi-dimensional WC–10Co4Cr coating may originate from the unique micro–nano structure and excellent properties, which can effectively obstruct the formation and propagation of cavitation erosion cracks.     

高含沙水流用水轮机叶片表面热喷涂WC/Co涂层的性能

通过高速火焰喷涂技术(高速氧-燃气喷涂,HVOF)在水轮机叶片用06Cr13不锈钢表面喷涂WC/Co涂层。采用金相显微镜、硬度计、万能试验机分析了WC/Co涂层的孔隙率、显微硬度及其与基体的结合强度;并在高含沙水流环境中通过冲蚀、汽蚀试验测试WC/Co涂层的耐冲蚀性能和耐汽蚀性能。结果表明:WC/Co涂层的孔隙率、显微硬度及其与基体的结合强度分别为0.68%、1211HV、70MPa;WC/Co涂层具有优良的耐冲蚀性能,冲蚀后其磨损量仅为06Cr13不锈钢基体的0.18倍;WC/Co涂层具有良好的致密度、结合力及强韧性,因此涂层也具有优良的耐汽蚀性能。     

Cavitation and electrochemical characteristics of thermal spray coating with sealing material

Steel applied in ocean environment is exposed to corrosion and cavitation and is subject to increasing damages. To prevent this, anti-corrosion thermal spray coating technique is widely used. The low-temperature thermal spray coating was performed with 85%Al–14.5%Zn–0.5%Zr for ship materials and various sealing materials were applied to improve its durability, and the electrochemical behavior and cavitation characteristics were observed. The results show that the sealing improves all the properties of the materials. Hybrid ceramic and fluoro-silicon sealing materials show good electrochemical characteristics, and the fluoro-silicon sealing material shows the best anti-cavitation characteristics.     

Structure and sliding wear behavior of 321 stainless steel/Al composite coating deposited by high velocity arc spraying technique

A typical 321 stainless steel/aluminum composite coating （321/Al coating） was prepared by high velocity arc spraying technique （HVAS） with 321 stainless steel wire as the anode and aluminum wire as the cathode. The traditional 321 stainless steel coating was also prepared for comparison. Tribological properties of the coatings were evaluated with the ring-block wear tester under different conditions. The structure and worn surface of the coatings were analyzed by scanning electron microscopy（SEM）, X-ray diffractometry（XRD） and energy dispersion spectroscopy（EDS）. The results show that, except for aluminum phase addition in the 32 l/Al coating, no other phases are created compared with the 321 coating. However, due to the addition of aluminum, the 32 l/Al coating forms a type of ＂ductile/hard phases inter-deposited＂ structure and performs quite different tribological behavior. Under the dry sliding condition, the anti-wear property of 32 l/Al coating is about 42% lower than that of 321 coating. But under the oil lubricated conditions with or without 32 h oil-dipping pretreatment, the anti-wear property of 321/AI coating is about 9% and 5% higher than that of 321 coating, respectively. The anti-wear mechanism of the composite coating is mainly relevant to the decrease of oxide impurities and the strengthening action resulted from the ＂ductile/hard phases inter-deposited＂ coating structure.     

Al含量对Ti1-xAlxN涂层组织结构、力学性能和铣削性能的影响

目的研究不同Al含量对Ti_(1-x)Al_xN涂层的影响,以获得铣削铸铁材料性能最佳的Ti AlN涂层。方法采用阴极电弧蒸发沉积法在WC-Co硬质合金表面制备两种不同Al含量的Ti_(0.5)Al_(0.5)N和Ti_(0.33)Al_(0.67)N涂层,通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和电子探针微区分析仪(EPMA)分析合金的微观组织和成分组成,通过CSM纳米硬度计和纳米划痕仪测定涂层的纳米硬度、弹性模量、抗塑性变形因子、显微硬度耗散系数MDP和划痕裂纹扩展阻力CPRs等性能指标,同时比较不同Al含量涂层刀片在铣削灰口铸铁HT250和球墨铸铁QT450时的性能和磨损机理。结果 Ti_(0.5)Al_(0.5)N和Ti_(0.33)Al_(0.67)N涂层主要物相均呈NaCl型面心立方结构,以(200)方向为择优取向,且高铝涂层的XRD衍射峰向高角度偏移量大于中铝涂层,说明高铝涂层具有更高的铝固溶量。与Ti_(0.5)Al_(0.5)N涂层相比,Ti_(0.33)Al_(0.67)N涂层的抗塑性变形因子较小,MDP和CPRs较大,表现出更优的塑性、韧性和膜基结合力。在铣削HT250和QT450时,Ti_(0.33)Al_(0.67)N涂层刀片的平均寿命分别为30、60 min,相比Ti_(0.5)Al_(0.5)N涂层,切削性能更好。结论对于Ti AlN涂层来说,提高Al的质量分数至67%可以获得更优的塑性、韧性和膜基结合力,在铣削HT250和QT450时,Ti_(0.33)Al_(0.67)N涂层刀片的切削性能较优。     

等离子喷涂强化H13钢铸铝压铸模实验研究

为解决H13钢铸铝压铸模普遍存在的抗热腐蚀能力差、强度低等问题,采用等离子喷涂工艺在H13钢基体上制备了Al2O3和Al2O3-TiO2两种硬质涂层。以喷涂电流、喷涂电压、喷涂距离为试验参数进行正交试验,采用MH-6型显微硬度仪和HSR-2M往复摩擦磨损试验机测试了涂层的显微硬度和磨损质量,通过对显微硬度的极差和方差分析,确定了影响涂层显微硬度的主次因素和显著因素,优化了喷涂工艺参数。结果表明,Al2O3-TiO2涂层的硬度982.0 HV,摩擦系数平均值为0.41～0.45,磨损量平均为0.89～0.93 mg;Al2O3涂层的硬度1446.2 HV,摩擦系数平均值为0.32～0.35,磨损量平均为0.58～0.62 mg。Al2O3涂层的性能较好,优化工艺参数为:电流为600 A,电压为65 V,喷涂距离为110 mm,预热温度为200℃。     

高速电弧喷涂Fe3Al/WC复合涂层高温冲蚀行为研究

采用自行研制的新型热喷涂Fe3Al/WC复合合金粉芯丝材,成功地用高速电弧喷技术制备出了Fe3Al金属化合物基金属陶瓷复合涂层。对涂层成分、显微组织、涂层相结构和组成进行了分析,结果表明,涂层由以Fe-26Al为主的Fe3Al基体相与约20%的WC、W2C和 a-Al2O3相组成。对比研究了Fe3Al/WC涂层和电站锅炉钢20 g从室温至650 ℃氧化环境条件下不同攻角的高温冲蚀磨损性能,结果表明Fe3Al/WC涂层的高温冲蚀磨损抗力高于20 g钢,650 ℃和30°攻角下的稳态相对冲蚀磨损抗力为20 g钢的3.14倍。温度对Fe3Al/WC涂层的冲蚀行为有较大影响：温度 < 450℃,涂层的冲蚀率变化不大,表现出塑性材料的冲蚀行为;温度 >450 ℃,涂层冲蚀率变化较大,呈现典型的脆性材料冲蚀磨损行为。并对其高温冲蚀磨损机理进行了分析。