基体表面粗糙度对涂层结合强度的影响

采用不同粒度的喷砂材料对基体表面进行喷砂粗化预处理,研究基体表面粗糙度的变化及其对等离子涂层和电弧涂层结合强度的影响.结果发现,基体表面粗糙程度对涂层与基体的结合强度有很大的影响.对于等离子喷涂,表面粗糙度应该存在一个最佳范围,并不是表面粗糙度越大,涂层与基体的结合就越好.喷涂方法不同,粗糙度的变化对涂层结合强度的影响不同.     

FEP/PPS共混涂层微观结构及其与钢基体的结合强度

以机械共混法在普通碳钢基体上制备了多种FEP/PPS共混改性防腐涂层,利用光学显微镜(OM)、电子探针(EPMA)研究了FEP/PPS共混涂层的微观结构、成分分布,采用拉伸法测定了FEP/PPS共混涂层与钢基体的结合强度,研究了共混组分PPS对复合防腐涂层结合强度的影响.结果表明,随着共混涂层中PPS组分的增加,共混涂层由典型的"海-岛结构"变为两相连续的"海-海结构",使涂层/钢基体结合强度有大幅度提高,拉断形式由涂层与基体界面光滑开裂,转变为涂层内聚开裂.     

预应力热处理对羟基磷灰石涂层相组成和结合强度的影响

设计不同角度的斜面工业纯钛柱,采用等离子法制备羟基磷灰石涂层,设计工装使涂层在预加相同正应力和不同切应力条件下进行热处理.利用电子拉伸实验机进行剪切结合强度测试,利用X射线衍射仪检测涂层的相组成与结晶度,探讨应力条件下热处理对涂层组成和涂层/基体结合强度的影响.研究表明:热处理中预加应力可以提高涂层的结晶度和涂层/基体的剪切结合强度.     

喷涂工艺参数对纳米NiCr/WC涂层与基体间结合强度的影响

以纳米NiCr/WC粉末为原料,采用活性燃烧超音速火焰喷涂技术制备了NiCr/WC金属陶瓷涂层。通过XRD衍射以及能谱分析等方法研究了工艺参数对纳米NiCr/WC涂层与基体之间结合强度的影响。结果发现,在喷涂材料确定的条件下,热喷涂涂层与基体之间的结合强度主要取决于热喷涂工艺。尤其是喷涂距离,对涂层与基体之间的结合强度的影响非常明显。     

CuNiCoBe合金表面等离子弧喷涂Cr3C2-NiCr涂层

利用等离子弧喷涂技术在结晶器CuNiCoBe基体上制备了Cr3C2-NiCr涂层,采用正交试验法研究了喷涂工艺参数对涂层与基体结合强度的影响,对拉伸断面的形貌和涂层的显微结构进行了观察和分析.结果表明,影响Cr3C2-NiCr涂层与CuNiCoBe基体结合强度的主次因素依次为:送粉速率＞主气流量＞喷涂距离＞喷涂功率;经正交试验优化后的喷涂工艺参数为:喷涂距离90mm,主气流量56.6L/min,送粉速率20 g/min,喷涂功率25 kW;优化后,涂层与基体的结合强度可达18.5 MPa;涂层截面的显微硬度分布符合正态分布.     

火焰喷涂尼龙1010涂层强度测量方法研究

利用理论分析与实验相结合的方法,模拟平面火焰喷涂,设计了一套简单、方便的平面结合强度拉拔实验模具及配套夹具,用于测量火焰喷涂聚合物涂层与基体的结合强度.试验结果表明:所得实验值与理论分析相符,当拉拔试件活塞直径为2mm左右时,比较适合用于火焰喷涂聚合物涂层与基体的结合强度的测量.证明这套模具在评价火焰喷涂聚合物涂层与基体结合强度方面有一定的实用价值.     

影响CVD金刚石涂层工具界面结合强度的因素及改进措施

化学气相沉积法制备金刚石涂层硬质合金工具综合了金刚石与硬质合金的优异性能,广泛应用于切削难加工材料。金刚石与硬质合金基体界面结合强度是评价金刚石涂层的一个重要性能指标。本文主要介绍了影响CVD金刚石涂层工具界面结合强度的主要因素,并对如何提高其界面结合强度的方法进行了较深入的探讨,同时科学论述了金刚石涂层结构的优化设计理念,以解决金刚石涂层附着强度低、表面粗糙度高等关键技术,这对如何提高硬质合金基体与金刚石涂层之间的界面结合强度具有一定的实际指导意义。     

TiN/TiAlN涂层Ti(C,N)基金属陶瓷刀具的切削性能

采用多弧离子镀技术在Ti(C,N)基金属陶瓷基体上沉积了TiN/TiAlN多层涂层,通过扫描电镜、涂层附着力自动划痕仪对其显微组织形貌和涂层的结合强度进行了分析,并对涂层和未涂层金属陶瓷铣刀以及硬质合金铣刀进行了切削0Cr18Ni9钢的试验.结果表明,多弧离子镀TiN/TiAlN涂层均匀,TiN/TiAlN多层涂层与金属陶瓷之间的结合强度高达57.52 N.TiN/TiAlN涂层金属陶瓷的切削性能明显优于未涂层金属陶瓷和硬质合会YW2,其平均寿命为硬质合金刀具的2倍.TiN/TiAlN涂层金属陶瓷刀具的失效形式主要是磨损和崩刃,没有涂层剥落现象,TiN/TiAlN涂层与基体的结合强度很好.未涂层金属陶瓷刀具的磨损形式主要是磨损和粘着.     

渗铝及扩散处理对电弧喷涂层结合强度的影响

利用电弧喷涂技术、渗铝和扩散处理工艺,在铸铁表面制作了具有微冶金结合的18-8不锈钢耐热耐蚀涂层.采用光学显微镜,SEM及X射线衍射等方法,对经过不同渗铝和扩散处理工艺得到的涂层的组织形貌,相结构及成分进行了分析研究.并采用热疲劳试验对渗铝和扩散处理后涂层的结合强度进行评价.结果表明,通过渗铝和扩散处理,涂层与基体之间产生了微冶金结合,涂层的结合强度得到了显著提高.并且渗铝时间过长不利于提高涂层结合强度,应合理控制渗铝时间.     

人工机械心瓣热解碳 / 石墨界面结合强度分析

目的研究人工心瓣热解碳涂层与基体结合强度的影响因素,从而分析提高人工心瓣寿命的途径。方法通过改进的剪切试验法,得到人工机械心瓣热解碳涂层/石墨基体的平均界面剪切结合强度。利用有限元分析软件ANSYS建立三维模型,对人工机械心瓣热解碳涂层/石墨基体的界面剪切应力进行分析,将分析结果与试验结果进行对比。利用ANSYS验证不同涂层厚度以及不同涂层弹性模量的情况下,界面剪切应力的变化情况。结果试验所得的平均界面剪切结合强度为5.535 MPa,有限元分析得到的平均结合强度值为5.98 MPa。随着涂层厚度的增加,涂层与基体结合强度降低;随着涂层弹性模量的增加,涂层与基体结合强度增大,但弹性模量并非越大越好,应有一个合适的值。结论 ANSYS分析是准确的。制备热解碳涂层时,应尽量薄一些,热解碳的弹性模量相对石墨应尽量大一些。     

面向工业设计的塑料表面铝涂层的结合强度

目的采用电弧喷涂方法在环氧树脂和ABS塑料表面喷涂铝涂层,研究涂层结合强度的影响因素。方法第一组试验是塑料表面喷砂后,喷涂铝涂层;第二组是塑料表面喷砂后,涂覆一层高强度环氧树脂结构胶,再喷涂铝涂层。选择喷涂气体压力、喷涂电流和喷涂距离三因素进行正交试验,采用粘结拉伸法测试结合强度,并用照相法测量铝液和环氧树脂塑料、Q235钢的接触角。结果本试验条件下,二种塑料电弧喷涂铝涂层结合强度的影响因素主次顺序为:空气压力喷涂电流喷涂距离。最优方案是:喷涂气体压力为0.7 MPa,喷涂电流为220 A,喷涂距离为160 mm。未涂覆高强度环氧树脂结构胶的涂层,结合强度最大不超过3 MPa;涂覆高强度环氧树脂结构胶的涂层,结合强度达到近20 MPa。铝液和Q235钢的接触角是45°,和环氧树脂塑料的接触角是135°。结论环氧树脂和ABS塑料表面电弧喷涂铝涂层的结合强度低的主要原因是铝液和它们之间的润湿性差。涂覆高强度环氧树脂结构胶后,喷涂工艺参数对涂层的结合强度影响不明显,结合强度受控于环氧树脂结构胶的粘接作用,使涂层的结合强度显著提高。     

不同工艺参数下超音速等离子喷涂层界面结合行为及其分形特性∗

随着研究不断深入，分形几何可以用来描述涂层的表面形貌和复杂性，分形维数可实现形貌结构的定性描述向定量表征转变。为研究超音速等离子喷涂层界面结合行为与其分形维数之间的关系，采用对比试验研究喷涂距离、喷涂电流等工艺参数对涂层结合界面形貌和结合强度的影响，并引入分形理论对界面结合行为进行定量表征，进而探究结合界面形貌、结合强度、分形维数三者的对应关系。结果表明：相比于喷涂电流，喷涂距离对分形维数的影响更为显著。当喷涂距离为 80 mm 和 100 mm 时，随着喷涂电流从 400 A 增大到 500 A，分形维数呈先减小后增大趋势，最小为 1.115 0；当喷涂距离为 120 mm 时，粒子在等离子焰流中的飞行时间增长，随电流增大，涂层界面分形维数则先增大后减小。界面分形维数与涂层结合强度之间存在着正相关的对应关系。当分形维数在一定范围内呈增大趋势时，涂层 / 基体结合界面处孔隙减少、结合强度增大。 因此，涂层 / 基体结合行为的分形特性研究对评价涂层质量具有重要意义。     

Finite-element evaluation and improvement of a test procedure for coating shear bond strength determination

In the research and development of thermal spraying coating systems for wear-resistance applications, it is essential to determine coating/substrate bond strength with a proper test procedure. This article describes mechanical evaluations of a widely adopted coating shear bond strength test procedure conducted via the finite-element method. Analyses of the stress distributions on the coating/substrate interface indicate that significant errors will be introduced if the standard test procedure is used to determine coating shear bond strength. A new test procedure with modified specimen geometry is proposed and then verified for effectiveness.     

Influence of ceramic thickness on residual stress and bonding strength for plasma sprayed duplex thermal barrier coating on aluminum alloy

NiCoCrAlY/8wt.%Y₂O₃–ZrO₂ coating was plasma sprayed on aluminum alloy to evaluate the effect of ceramic thickness on residual stress and bonding strength. A new stress calculation method based on Stoney equation and substrate-removal technique was proposed. Stress in both bond coat and ceramic was studied. With the increase of ceramic thickness, the residual stress in both layers was firstly compressive then turned tensile. The large thermal expansion coefficient of the substrate played an important role in residual stress formation when the ceramic was thin. However, the intrinsic deposition stress took a dominant position when the ceramic coating turned thicker. The bonding strength decreased and the location of the fractured surface moved toward the ceramic surface. The moving of the surface was mainly resulted from the variation of stress gradient and the weakness of high porosity zone near the bond coat–ceramic interface.     

Bonding Mechanisms in Cold Spraying: The Contributions of Metallurgical and Mechanical Components

The mechanism of bonding in cold spraying is still a matter of some debate. In this work, copper has been cold sprayed onto aluminium alloy substrates, the surfaces of which had been prepared in a variety of ways. The coating-substrate bonding was assessed via a novel intermetallic growth method along with adhesive pull-off testing, and related to the substrate preparation method. The bond strength has been rationalized in terms of a modified composite strength model, with two operative bonding mechanisms, namely (i) metallurgical bonding and (ii) mechanical interlocking of substrate material into the coating. In most cases, mechanical interlocking is able to account for a large proportion of the total bond strength, with metallurgical bonding only contributing significantly when the substrate had been polished and annealed prior to spraying. In addition, grit-blasting has been shown to significantly reduce the bond strength compared to other substrate preparation methods.     

物理气相沉积TiN涂层结合力的研究现状与展望

物理气相沉积涂层质量指标主要通过涂层与基体结合强度来评定,因此,结合力决定了涂层是否可用.镀层的结合力强度既取决于膜/基界面的物理和化学相互作用,同时也取决于界面区的微观结构.本文阐述了薄膜中残余应力形成的原因,并分析了其引起的机理.综述了中间层Ti薄膜,梯度镀层及渗氮层与基体界面结合力的关系,从而提高界面结合强度.为合理设计PVD新型涂层提供依据.     

On the Interplay Between Adhesion Strength and Tensile Properties of Thermal Spray Coated Laminates—Part II: Low-Velocity Thermal Spray Coatings

In this two-part study, uniaxial tensile testing was used to evaluate coating/substrate bonding and compared with traditional ASTM C633 bond pull test results for thermal spray (TS) coated steel laminates. In Part I, the rationale, methodology, and applicability of the test to high-velocity TS coatings were demonstrated. In this Part II, the method was investigated for low-velocity TS processes (air plasma spray and arc spray) on equivalent materials. Ni and Ni-5wt.%Al coatings were deposited on steel substrates with three different roughness levels and tested using both uniaxial tensile and ASTM C633 methods. The results indicate the uniaxial tensile approach provides useful information about the nature of the coating/substrate bonding and goes beyond the traditional bond pull test in providing insightful information on the load sharing processes across the interface. Additionally, this proposed methodology alleviates some of the longstanding shortcomings and potentially reduces error associated with the traditional ASTM C633 test. The mechanisms governing the load transfer between the substrate and the coating were investigated, and the influence of Al in the coating material evaluated.     

The Influence of the Coating Deposition Process on the Interdiffusion Behavior Between Nickel-Based Superalloys and MCrAlY Bond Coats

In this work, interdiffusion between two nickel-based superalloys and two MCrAlY bond coats is investigated. The MCrAlY bond coats were applied using two different spraying processes, high velocity oxygen fuel spraying (HVOF) and low-pressure plasma spraying. Of primary interest is the evolution of Kirkendall porosity, which can form at the interface between substrate and bond coat and depends largely on the chemical compositions of the coating and substrate. Experimental evidence further suggested that the formation of Kirkendall porosity depends on the coating deposition process. Formation of porosity at the interface causes a degradation of the bonding strength between substrate and coating. After coating deposition, the samples were annealed at 1050 °C for up to 2000 h. Microstructural and compositional analyses were performed to determine and evaluate the Kirkendall porosity. The results reveal a strong influence of both the coating deposition process and the chemical compositions. The amount of Kirkendall porosity formed, as well as the location of appearance, is largely influenced by the coating deposition process. In general, samples with bond coats applied by means of HVOF show accelerated element diffusion. It is hypothesized that recrystallization of the substrate material is a main root cause for these observations.     

A method for determining the bonding strength of a silver coating with a silicon substrate

A method for determining the bonding strength of a silver coating with a silicon substrate is described. Various high-strength adhesives are tested and the optimum adhesive for the determination of the bonding strength of the silver coating with the silicon substrate on the basis of the bonding method is selected.     

基体表面形貌对Ni/Fe热喷涂及结合强度影响的原子模拟

通过分子动力学方法模拟了基体表面形貌对热喷涂的影响。研究了柱状粗糙表面和光滑表面对团簇展平、基体缺陷演化、应力分布、涂层与基体结合强度的影响。结果表明,基体表面形貌对热喷涂结合强度影响显著,粗糙表面不仅增加了团簇与基体的实际接触面积,提高了附着力,而且在界面结合处形成锚固效应,从而提高了界面结合强度。同时,基体表面形貌改变了界面区域的应力分布,柱状粗糙表面可以减小应力集中效应,降低临界应力,减轻对基体的损伤。此外,粗糙表面会阻碍团簇的滑移,减小了展平比。