爆炸喷涂Al-Cu-Cr准晶涂层的组织及硬度研究

为了研究热喷涂工艺对爆炸喷涂Al-Cu-Cr准晶涂层组织和硬度的影响规律,采用三种爆炸喷涂工艺参数在Q235A低碳钢基体上制备涂层,借助XRD、SEM和OM等技术手段对粉末和涂层的组织结构进行分析,并检测涂层横截面的孔隙率和显微硬度.结果表明,用于喷涂的Al65Cu20Cr15准晶粉末中含有二十面体准晶相i-Al65Cu24Cr11和极少量具有单斜结构的晶体相θ-Al13Cr2(即Al83Cu4Cr13);而爆炸喷涂涂层中除i和θ两相外,生成了新相--体心立方结构的α-Al69Cu18Cr13(准晶i的晶体类似相)和Al203相.涂层呈典型层状结构,其它条件不变的情况下,涂层中各晶体相与准晶相i最强峰衍射强度的比值α/i、θ/i和Al2O3/i随爆炸喷涂工作气体流速的成比例提高而增加,同时涂层截面的孔隙率下降而显微硬度HV0.1升高.     

爆炸喷涂Al-Cu-Fe准晶涂层性能分析

目的 提高准晶涂层内部准晶相含量,进而研究Al-Cu-Fe准晶涂层的各项性能。方法 采用爆炸喷涂的方式在2A12铝合金基底上制备了Al-Cu-Fe准晶涂层。借助SEM、XRD等手段对Al-Cu-Fe准晶粉体的组织形貌、物相形成进行研究。采用显微硬度计、拉力试验机测试涂层的力学性能。采用比热容测试仪、激光热导仪检测涂层的热性能。使用摩擦磨损试验仪研究了涂层的摩擦磨损性能。结果 水雾化法制成的Al-Cu-Fe准晶粉体主要包含准晶相和少量的β-Al_42.54Cu_34.65Fe_22.81相,准晶含量为73%。882℃为准晶相的熔点,粉体在800℃的退火温度下准晶含量能达到98.7%。涂层在700℃下比热容为0.749 J/(g·K),热导率为5.913W/(m·K)。涂层的显微硬度为569.4HV0.3,经退火处理最高硬度可达658.33HV0.3。涂层的结合强度为33.25 MPa,退火处理后结合强度为58.75 MPa。涂层在不同载荷和温度下,摩擦因数为0.768～0.512(均低于基体),在15 N和20 N的载荷下磨损率...     

爆炸喷涂工艺参数对AlCuFeSc准晶涂层力学性能的影响

目的 研究爆炸喷涂工艺参数对AlCuFeSc准晶涂层力学性能的影响规律,进一步提升铝合金表面AlCuFeSc准晶涂层的性能。方法 采用爆炸喷涂工艺制备准晶涂层,以正交试验方法对爆炸喷涂氧燃充枪比、喷涂距离、喷涂频率3个影响涂层性能的关键参数进行优化。借助显微硬度计、拉力试验机研究涂层的力学性能。采用SEM、XRD、EDS等手段表征粉末及涂层的微观物相结构。结果 在试验参数范围内,以涂层的表面硬度和结合强度性能为主要判定指标,各因素对涂层性能的影响从大到小依次为氧燃充枪比、喷涂距离、喷涂频率。综合考量涂层表面硬度和结合强度2个指标,得到了AlCuFeSc涂层的最佳制备工艺,氧燃充枪比为56%,喷涂距离为210 mm,喷涂频率为1次/s。在该最佳工艺参数下制备的准晶涂层致密且与铝合金基体结合良好,涂层表面硬度为583.4HV0.3,结合强度为63.24 MPa,孔隙率为0.648%,准晶相的含量为69%。结论 采用最佳工艺参数制备的AlCuFeSc准晶涂层相较于非最佳工艺参数喷涂涂层,其性能得到较大提高,可为未来准晶涂层的应用提供参考。     

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.     

等离子喷涂WC-Co涂层的微观组织及硬度

以普通低碳钢Q235A为基体，钴基碳化钨陶瓷粉末WC-12Co为热喷涂材料，采用低功率（5．2kW～9．1kW）内送粉等离子喷涂方法，在保持等离子弧电流恒定的情况下，通过改变弧电压来制备不同功率下的WC-Co陶瓷涂层。利用扫描电子显微镜（SEM）和X射线衍射仪对涂层的显微组织和相结构进行观察与分析，并使用MH-6维氏硬度仪测量涂层的显微硬度HV，研究喷涂条件对形成的WC-Co陶瓷涂层微观组织、相组成和硬度的影响规律。结果表明：原始喷涂粉末的XRD图谱中仅能观察到主相WC和极少量的金属Co，而低功率等离子喷涂WC-Co陶瓷涂层中则除了WC相以外，还含有W2C，Co3W3C，Co3W9C4等其它相，并且随着等离子喷涂功率的增加，WC衍射峰强度降低，而包括W2C在内的其它相衍射峰强度升高。等离子喷涂WC-Co涂层微观组织为大量硬质相（WC，W2C，CO3W3C或Co3w9C4）颗粒弥散分布于较软的富Co粘结剂之中。保持等离子弧电流130A不变，涂层显微硬度随弧电压升高呈现先下降后上升的变化规律，并且电压70v时涂层具有最高的显微硬度。     

Al-Cu-Cr准晶的力学性能

用雾化法制得的Al65Cu20Cr15准晶粉末与纯铝热压合成复合材料,在热压和热处理状态下复合材料中的颗粒为尺寸在35-160μm范围的Al-Cu-Cr二十面体准晶和十次准晶及其类似相。采用维氏压痕实验技术测试估算了Al-Cu-Cr准晶颗粒的力学性能。结果表明,热压状态下的Al-Cu-Cr二十面体准晶材料的断裂韧性和抗拉强度约为0.82MPa.m1/2和715MPa,经退火处理后得到的Al-Cu-Cr十次准晶及其类似相材料的断裂韧性和抗拉强度约为1.07MPa.m1/2和879MPa,淬火处理后约为1.15MPa.m1/2和1054MPa,与Al-Cu-Cr二十面体准晶材料相比有所提高,淬火态的Al-Cu-Cr十次准晶材料的断裂韧性和抗拉强度最高。     

电热爆炸喷涂WC/Co涂层组织和性能研究

利用电热爆炸喷涂技术,在45钢表面制备了WC／Co耐磨涂层,使用SEM和XRD分析了涂层的组织与相结构,使用显微硬度计和纳米压痕仪测试了涂层的硬度和弹性模量。结果发现,电热爆炸喷涂WC／Co涂层致密,无明显的层状结构;涂层的显微硬度最高达到了2836HV0．1,平均为1704HV0．1;纳米压痕仪测得涂层的弹性模量为346．8GPa;涂层的相组成主要为WC和W2C;在涂层与基体的结合区,出现柱状晶,证明涂层与基体主要是冶金结合。     

喷涂工艺对超音速火焰喷涂Al-Cu-Fe-Si准晶合金涂层性能的影响

目的使用活性燃烧高速燃气喷涂(AC-HVAF)方法制备高质量的Al-Cu-Fe-Si准晶涂层,研究喷涂工艺对涂层性能的影响。方法采用气雾化Al-Cu-Fe-Si准晶合金粉末,利用AK02T型AC-HVAF喷涂系统制备Al-Cu-Fe-Si准晶涂层材料。通过X射线衍射及扫描电镜观察分析准晶合金粉末和涂层的组织与结构,通过电化学工作站、显微硬度计和接触角测试仪等手段分析准晶合金涂层的耐蚀性、显微硬度及抗粘性能。结果对气雾化准晶Al-Cu-Fe-Si合金粉末的研究发现,冷却速率显著影响准晶合金粉末的组织,在冷却速率较快的粉末中形成胞状晶组织,准晶I相含量较高。对准晶合金涂层进行热处理,高温退火显著提高了涂层的硬度,950℃退火12 h后,硬度值达到(724±153)HV0.1。分别对准晶合金涂层和基体45~#钢的接触角进行测量,准晶合金涂层的接触角最大为95°,而45~#钢的仅为79°。通过电化学工作站测试比较涂层的耐蚀性,发现在3.5%(质量分数)的Na Cl溶液中,喷涂在45~#钢和5052铝合金基体上的涂层腐蚀电流密度J_(corr)分别为6.8×10~(-6),2.0×10~(-7)A/cm~2。结论不同粒径的气雾化准晶合金粉末的相组成不同,选择合适的粒径是保证铝基准晶合金涂层质量的前提。对涂层进行合适的热处理可以有效地提高涂层的显微硬度,铝基准晶合金涂层的接触角较45~#钢的高,提高了基体的抗粘性。不同基体上制备的准晶合金涂层的耐蚀性有很大差异,5052铝合金基体上的准晶涂层耐蚀性优于喷涂在45~#钢基体上的涂层。     

等离子喷涂WC-Co涂层的微观组织及硬度

以普通低碳钢Q235A为基体,钴基碳化钨陶瓷粉末WC-12Co为热喷涂材料,采用低功率(5.2 kW～9.1 kW)内送粉等离子喷涂方法,在保持等离子弧电流恒定的情况下,通过改变弧电压来制备不同功率下的WC-Co陶瓷涂层.利用扫描电子显微镜(SEM)和X射线衍射仪对涂层的显微组织和相结构进行观察与分析,并使用MH-6维氏硬度仪测量涂层的显微硬度HV,研究喷涂条件对形成的WC-Co陶瓷涂层微观组织、相组成和硬度的影响规律.结果表明:原始喷涂粉末的XRD图谱中仅能观察到主相WC和极少量的金属Co,而低功率等离子喷涂WC-Co陶瓷涂层中则除了WC相以外,还含有W2C,Co3W3C,Co3W9C4等其它相,并且随着等离子喷涂功率的增加,WC衍射峰强度降低,而包括W2C在内的其它相衍射峰强度升高.等离子喷涂WC-Co涂层微观组织为大量硬质相(WC,W2C,Co3W3C或Co3W9C4)颗粒弥散分布于较软的富Co粘结剂之中.保持等离子弧电流130 A不变,涂层显微硬度随弧电压升高呈现先下降后上升的变化规律,并且电压70 V时涂层具有最高的显微硬度.     

热处理工艺对超音速火焰喷涂Al-Cu-Fe准晶涂层性能影响

目的 使用超音速火焰喷涂(HVOF)方法制备Al-Cu-Fe准晶涂层,研究热处理温度对涂层中准晶相含量和性能的影响以及封孔处理对涂层耐蚀性的改善。方法 以304不锈钢为基体和真空雾化Al-Cu-Fe准晶粉末为热喷涂材料,采用超音速火焰喷涂方法制备准晶涂层,并进行550～700℃热处理。利用透射电镜、扫描电镜、光学显微镜、能谱分析仪和X射线衍射仪分析准晶粉末和涂层的衍射花样、微观形貌、成分和相结构。分别使用显微硬度仪和电化学工作站对比测量304不锈钢和准晶涂层的硬度和耐蚀性能。结果 粉末中二十面体准晶相(I相)为主相,并伴生准晶类似相(β相)。经过超音速火焰喷涂后,涂层中I相和β相的含量分别为78.7%和21.3%,相组成与原始粉末接近。550℃和600℃热处理1h后,涂层中β相消失,I相占比进一步上升,并伴随Al₂Cu(θ相)产生。随着热处理温度继续升高至650℃,β相开始重新析出;当热处理温度升至700℃,β相占比增至13.5%。热处理后准晶涂层的最高硬度为674HV,为304不锈钢硬度(182HV)的3.7倍。准晶涂层经过热处理和表面封孔后,其在3.5%NaC...     

Control of structural and phase processes in detonation spraying of coatings

Issues of obtaining coatings with optinum structure and properties from nickel-clad powdered aluminium oxide are studied. A production method of metal–ceramic composition is offered, the ceramic component gradually increasing from the lower layer to the upper one, ensuring optimal properties of the coating.     

Dynamic hardness of detonation sprayed WC-Co coatings

The objective of the present work was to determine the dynamic hardness of WC-Co coatings from the dynamic hardness of the coating substrate system. It was also the purpose of this work to evaluate the influence of coating composition, coating thickness, and substrate materials on the dynamic hardness of the coating. To achieve the above-mentioned objectives, WC-12%Co and WC-17%Co coatings were deposited by detonation spraying on three different substrate materials: mild steel, commercially pure (CP) aluminum, and CP titanium. The dynamic hardness of the coating/substrate composite was evaluated by a drop weight system. The dynamic hardness of the coating independent of the substrate was determined from the dynamic hardness of the coating/substrate composite.     

爆炸喷涂CoNiCrAlY-Al2O3涂层的组织及高温耐磨性研究

采用三种爆炸喷涂工艺在SCH19耐热钢基体上制备CoNiCrAlY-Al2O3高温耐磨涂层,借助XRD、SEM和EDS等技术对涂层的组织结构进行分析,并检测涂层的表面粗糙度、显微硬度和高温磨损失重。结果表明,涂层由γ-Ni（Co,Cr）、γ’-Ni3Al和α-Al2O3组成,涂层呈典型的层状结构,适当提高乙炔氧气流量比,可改善涂层的组织结构,并且使其在900℃的高温下具有更优异的耐磨性能。     

爆炸喷涂WC-Co/CoMoCrSi复合涂层的组织与性能

为了提高CoMoCrSi涂层的结合强度和力学性能,采用爆炸喷涂技术制备了WC-12Co涂层作为过渡层的WC-Co/CoMoCrSi复合涂层,借助SEM和EDS等手段分析了涂层截面组织形貌和化学元素组成,采用显微硬度计、万能拉伸机及销盘式摩擦磨损试验机等研究了涂层的力学及摩擦磨损性能。结果表明：在氧燃充枪比为60%的喷涂参数下,制备WC-Co/CoMoCrSi复合涂层平均结合强度高达66 MPa,涂层截面组织致密、均匀,孔隙率小于0.6%,平均显微硬度为667 HV0.1,复合涂层摩擦因数0.53~0.56,具有优异的耐磨性能。     

Al-Cu-Cr quasicrystalline coatings prepared by low power plasma spraying

Al-Cu-Cr quasicrystalline coatings were prepared by low power plasma spraying with axially-fed powder systerm. The Al₆₅Cu₂₀Cr₁₅ powders were deposited on AISI 1045 steel substrate at the power ranged from 4.0 to 6.0 kW. The effects of H₂/Ar flow ratio on the phase composition, microstructure and microhardness properties of the as-sprayed coatings were investigated. The XRD results showed that the original powders and as-sprayed coatings contained a predominant icosahedral quasicrystalline phase I-Al₆₅Cu₂₄Cr₁₁ and three minor crystalline phases, including a body-centered cubic α-Al₆₉Cu₁₈Cr₁₃, a monoclinic θ-Al₁₃Cr₂ (i.e. Al₈₃Cu₄Cr₁₃) and a hexagonal ε-Al₂Cu₃. A qualitative analysis on the XRD patterns indicated that the volume fraction of any crystalline phase (α, ε or θ) in the coatings increased, while the quasicrystalline I-phase decreased with increasing hydrogen content in the plasma gas. As H₂/Ar flow ratio increased from 4.8% to 18.8%, the coating hardness increased whilst its porosity decreased, and they reached the maximum (4.98 Gpa) and the minimum (8%) respectively. However, with increasing H₂ content further, the hardness of the coating slightly decreased and its porosity increased because of the excessive vaporization of aluminum at higher plasma energy.     

Microstructure and properties of thermally sprayed silicon nitride-based coatings

The preparation of thermally sprayed, dense, Si₃N₄-based coatings can be accomplished using composite spray powders with Si₃N₄ embedded in a complex oxide binder matrix. Powders with excellent processability were developed and produced by agglomeration (spray drying) and sintering. Optimization of the heat transfer into the powder particles was found to be the most decisive factor necessary for the production of dense and well-adhering coatings. In the present work, different thermal spray processes such as detonation gun spraying (DGS), atmospheric plasma spraying (APS) with axial powder injection, and high-velocity oxyfuel spraying (HVOF) were used. The coatings were characterized using optical and scanning electron microscopy (SEM), x-ray diffraction (XRD), and microhardness testing. The wear resistance was tested using a rubber wheel abrasion wear test (ASTM G65). In addition, thermoshock and corrosion resistances were determined. The microstructure and the performance of the best coatings were found to be sufficient, suggesting the technical applicability of this new type of coating.     

Characteristics of high hardness alumina coatings formed by gas tunnel plasma spraying

High hardness alumina coatings were formed at atmospheric pressure by gas tunnel plasma spraying, and the characteristics of these coatings were investigated. The hardness on the cross section of the alumina coating at a short spraying distance was more than 1300 HV, and the thickness of the hard layer increased with an increase of power input. The microstructure of the alumina coating was investigated by microscopy and x-ray diffraction (XRD) methods. It was ascertained that the cell size was small (∼10 μn), and α-alumina was dominant in the high hardness layer of the coating. Finally, the effect of plasma energy was estimated from these results.     

Formation of high hardness zirconia coatings by gas tunnel type plasma spraying

The high hardness zirconia (ZrO₂) coatings could be obtained at an atmospheric pressure by using a gas tunnel type plasma spraying. The characteristics of these high hardness ZrO₂ coatings were investigated. The Vickers hardness of the ZrO₂ coating at a short spraying distance was very high; a high hardness of more than H_v=1200 was achieved at the surface side of the coating. The microstructure of the obtained high hardness ZrO₂ coating was also investigated by the microscopic method. And the characteristics of the high hardness ZrO₂ coating was discussed in comparison with that of the coating formed by the conventional type plasma spraying. It was clarified that the ZrO₂ coating of the gas tunnel type was not only much harder but also less porous than that of the conventional type.     

超音速等离子喷涂非晶涂层微观结构与摩擦学性能

采用新一代超音速高能等离子喷涂(SAPS)技术制备了Fe基和Mo基两种非晶涂层,对涂层的微观结构与摩擦学性能进行对比分析。结果表明,SAPS喷涂Fe基和Mo基非晶涂层内部孔洞少、结构致密性高。与Fe基涂层相比,具有更低孔隙率的Mo基涂层在摩擦过程中表现出更低的磨损率(1.1×10^-4 μm·N^-1·s^-1),耐磨性更优。涂层的磨损机理均以磨粒磨损和疲劳磨损为主,并伴随着磨屑氧化。