螺杆空压机橡胶涂层转子的有限元分析

结合橡胶的优点,对双螺杆空压机转子进行橡胶涂层改进,并验证其力学性能。通过SolidWorks软件对双螺杆空压机阴阳转子进行三维建模并装配,得到一对相互啮合的无橡胶涂层的阴阳转子装配模型;建立含有橡胶涂层的阴阳转子装配模型,并保证几何尺寸与无橡胶涂层的阴阳转子相同;计算转子转矩的大小、设置边界条件,并通过有限元分析软件分别对无橡胶涂层的阴阳转子和有橡胶涂层的阴阳转子进行有限元仿真分析。结果表明：无橡胶涂层转子所受最大等效应力为479.37 MPa、最大等效弹性应变为0.002 7 mm;有橡胶涂层的转子所受最大等效应力为318.25 MPa、最大等效弹性应变为0.262 6 mm。橡胶涂层具有降低转子等效应力、提高转子等效弹性应变的作用。研究结果为增加螺杆压缩机转子使用寿命、提高气密性和效率提供了新的改进思路。     

扭转载荷作用下熔接涂层与基体结合界面处应力特性仿真研究

目的通过有限元仿真获得熔接涂层与基体结合界面处的应力分布特性,得到熔接涂层与基体的力学性能匹配性。方法应用ABAQUS有限元软件,将模型沿轴向和径向剖切,讨论不同扭矩载荷下镍基合金涂层和基体轴结合界面的应力分布规律,分析涂层厚度对结合界面处应力的影响。结果从模型剖切后采样结点的应力变化曲线看,基体和涂层的内部应力变化均匀,在基体和涂层结合处应力存在突变,涂层上的应力大于基体上的应力。涂层厚度从0.5 mm增大到1.0 mm时最大应力减小量约为18 MPa,从1.0 mm增大到2.5 mm时最大应力的减小量约为1 MPa,涂层厚度大于1.0 mm后最大应力减小量变化不明显。结合面两侧涂层和基体应力差值的最大值Δσ_(max)随着涂层厚度的增大有所减小,在涂层厚度小于1.0 mm时,变化较为明显。结合面底面处的应力突变随涂层厚度的增加而略有减小。结论在涂层和基体结合界面处存在应力突变,最大应力出现在涂层外表面的中心位置,增大涂层厚度可以减小应力突变,在涂层厚度较小时效果明显。     

HVOF碳化钨金属陶瓷涂层对基体疲劳性能影响的研究现状

由超音速火焰喷涂（HVOF）制备的碳化钨金属陶瓷涂层,具有接近完全致密、结合强度高、硬度高等优势。本文综述了金属表面HVOF碳化钨金属陶瓷涂层疲劳寿命影响的研究现状,并分析了产生疲劳裂纹的原因,影响疲劳寿命的原因有涂层与基体的性能差异、喷砂引入的缺陷、残余应力及涂层制备工艺等的影响。改进措施有涂层设计、基体不做喷砂或喷丸替代喷砂等改变前处理工艺、获得或提高涂层压应力、减少碳化物的分解、合理的工艺参数（如高的速度）、合适的涂层厚度、选用高含量粘结物的碳化钨金属陶瓷粉末、合适的涂层后处理方法等措施。     

双涂层界面接触应力分析

目的研究在接触应力作用下,双涂层的总厚度及厚度比对其界面应力的影响规律。方法采用有限元方法研究两个界面,即涂层与基底界面和涂层间界面的Mises应力突变量和界面最大剪应力。结果总厚度一定时,涂层厚度比变化对涂层/基底界面应力的影响较小,而对涂层间界面应力的影响明显。对于薄涂层,涂层间界面Mises应力突变量和最大剪应力随着中间层厚度比例的增大而减小;对于厚涂层,涂层间界面Mises应力突变量和最大剪应力随着中间层厚度比例的增大而减小。涂层厚度比一定时,随着涂层总厚度增加,涂层间界面Mises应力突变量和最大剪应力先增大,后减小。结论双涂层的总厚度及厚度比对其界面应力有显著影响。     

双涂层界面接触应力分析

目的研究在接触应力作用下,双涂层的总厚度及厚度比对其界面应力的影响规律。方法采用有限元方法研究两个界面,即涂层与基底界面和涂层间界面的Mises应力突变量和界面最大剪应力。结果总厚度一定时,涂层厚度比变化对涂层/基底界面应力的影响较小,而对涂层间界面应力的影响明显。对于薄涂层,涂层间界面Mises应力突变量和最大剪应力随着中间层厚度比例的增大而减小;对于厚涂层,涂层间界面Mises应力突变量和最大剪应力随着中间层厚度比例的增大而减小。涂层厚度比一定时,随着涂层总厚度增加,涂层间界面Mises应力突变量和最大剪应力先增大,后减小。结论双涂层的总厚度及厚度比对其界面应力有显著影响。     

烧结法制备碳化钨复合涂层研究

采用烧结法制备碳化钨复合涂层.采用在45钢基体上涂覆镍基自熔合金及碳化钨粉末工艺,通过真空烧结,制得了性能优良的硬质涂层.分析了所制备的涂层组织、性能及与基体间的界面结合状况,结果表明:涂层与母材之间具有良好的结合特性.所制备的碳化钨复合涂层硬度HRC为60～65.     

热障涂层热疲劳寿命预测模型研究

目的 建立热障涂层寿命预测模型,并研究涂层寿命预测与各种应力应变信息的相关性。方法 首先利用带热障涂层圆管试验结果,将涂层界面简化为余弦曲线,建立了相应的二维轴对称有限元模型;然后根据热障涂层疲劳试验结果,结合线性疲劳累积理论和Manson–Coffin低周疲劳模型,建立了热障涂层的寿命预测模型,并将拟合问题转化为寻优问题,使用遗传算法确定寿命预测模型中的系数;最后基于热障涂层试验的微观照片确定出危险点位置,选取正向、剪切、等效和通过二向应力应变分析方法提取垂直于余弦曲面形貌的11种应力应变信息进行寿命预测,并分析了寿命预测的最大误差和平均误差,对分析的结果进行了验证。结果 采用等效应变范围进行涂层寿命预测的最大误差和平均误差最小,分别为50%和21%,涂层寿命与等效应力的相关性最大。采用等效应变进行寿命预测的结果与文献中的结果相比,最大误差降低了169.1%,整体的寿命预测值从±2倍分散带之内缩小到了±1.5倍分散带之内。采用等效应变范围进行不同工况下的涂层寿命预测,预测结果为130次循环,试验结果为160次循环,寿命预测的结果较好。结论 证明了所建立模型的正确性与准确性,为涂层寿命...     

热障涂层高温氧化生长应力预测

基于Clark氧化生长应变率理论和Wagner氧化模型给出了涂层高温生长应力公式,计算预测了热障涂层中氧化生长应力随时间的演化规律;利用光致发光分析技术对氧化层的应力进行了实验测试,并对两种结果进行了比较和分析。结果表明,本文给出的热障涂层高温氧化生长应力模型预测与实验结果符合     

三维多粗糙峰涂层等效应力分析与表征

利用有限元方法建立了刚性平面与多粗糙峰涂层的弹性接触模型,研究了刚性平面分别与二维涂层粗糙峰、三维涂层粗糙峰的接触状态,揭示了涂层/基体弹性模量比、涂层厚度、粗糙峰问距、刚性平面压下深度对涂层粗糙峰表面、涂层/基体界面等效应力分布及涂层基体变形的影响规律.计算结果表明:压下深度对涂层粗糙峰表面最大等效米塞斯应力的影响最大,涂层厚度和涂层/基体弹性模量比的影响次之,粗糙峰间距的影响最小;增大涂层厚度,减小压下深度、粗糙峰间距和低弹性模量比,会使得最大等效应力值显著降低.     

烧结法制备碳化钨复合涂层研究

采用烧结法制备碳化钨复合涂层。采用在45钢基体上涂覆镍基自熔合金及碳化钨粉末工艺，通过真空烧结，制得了性能优良的硬质涂层。分析了所制备的涂层组织、性能及与基体间的界面结合状况，结果表明：涂层与母材之间具有良好的结合特性。所制备的碳化钨复合涂层硬度HRC为60-65。     

电火花沉积钨涂层的温度场和残余应力有限元模拟

目的 通过模拟钢基体表面电火花沉积钨涂层过程中的熔池区域温度场变化及其残余应力分布,以便更好地理解电火花沉积钨涂层的工艺过程,得到钨涂层成膜过程中的温度场分布和残余应力形成机制.方法 采用电极低速旋转与上下点动相结合的电火花沉积工艺,由点到线、再到面的沉积顺序,在钢基体表面均匀制备抗烧蚀钨涂层.同时,采用ANSYS仿真...     

NAK80模具钢表面激光熔覆Ni基碳化钨合金涂层的组织和性能

采用激光熔覆技术,在NAK80模具钢表面制备了Ni基碳化钨合金涂层.研究了激光熔覆涂层的组织结构特点及形成规律,测试分析了其显微硬度的分布特征.结果表明:涂层与基体之间呈良好冶金结合,熔覆层组织主要由树枝晶Cr<,23>C<,6>、未熔碳化钨颗粒相、γ-Ni固溶体及少量分布于固溶体中的NiCr和CrB<,2>相组成;涂...     

三螺杆泵的温度场及热力耦合分析

为适应三螺杆泵高速、高压、大流量的发展趋势,严格控制螺杆变形及其相关间隙以减少泵内泄漏是关键。以三螺杆泵为研究对象,将泵内温度场作为载荷施加在主、从动螺杆表面,并进行温度-结构耦合的数值模拟分析。研究不同工况下三螺杆泵内温度和工作扭矩使主、从动螺杆产生的变形规律,并对比与主、从动螺杆在各单独物理场作用下和耦合作用下的变形和应力变化。结果表明:主、从动螺杆的热变形比力矩变形更明显。随着工作温度升高,主、从动螺杆的热变形量增大,主、从动螺杆产生的热应力与工作温度呈正比关系;在同一工作温度下,主、从动螺杆在X、Y、Z 3个方向的变形量均增加,而Z方向的变形量远大于X和Y方向的变形量。     

Microstructure and cutting performance of CrTiAlN coating for high-speed dry milling

Using a closed field unbalanced magnetron sputtering system, the cemented carbide end mills were coated with a CrTiAlN hard coating, which consisted of a Cr adhesive layer, a CrN interlayer and a CrTiAlN top layer. The microstructure and mechanical properties of the coating were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro indentation and scratch test. The cutting performance of the coated end mills were conducted by high-speed dry milling hardened steel (P20, HRC 45). The results indicates that the coating is composed of (Cr, Ti, Al)N columnar grains with nanolayers. The coating exhibits good adhesion to cemented carbide substrate and high microhardness of around 30 GPa. The coated end mills show significant improvement on tool life and much lower cutting force as compared to the uncoated ones. And the related mechanisms were discussed.     

Analysis of tool wear and residual stress of CVD diamond coated cemented carbide tools in the machining of aluminium silicon alloys

Aluminium alloys have found increasing applications in the automotive and aeronautical industries in recent years. Due to their extraordinary properties however, the machining of these alloys still poses difficulties, and requires the optimized combination of cutting tool material and geometry. The potential of CVD diamond coated carbide tools has been demonstrated in recent years, however tool wear and short tool life remain as issues to be resolved. Key to increasing the tool life of CVD diamond coated tools is the further development of the coating process to optimize the coating adhesion. An understanding of the substrate and coating residual stress profiles must be gained in order to achieve this. Compressive residual stresses in cutting tools can lead to a higher crack resistance, but also to early coating delamination and tool failure. To analyze the influence of residual stresses on the coating quality and tool life, the residual stress profiles of tungsten carbide substrates and CVD diamond coatings were measured using X-ray and synchrotron radiation. The influence of the tungsten carbide substrate type and the CVD diamond coating process on the residual stress profiles was thus determined. In order to analyze the performance of the coated tools and the influence of the residual stresses on the tool lifetime, machining tests were performed with two aluminium silicon alloys. The tool wear, tool lifetime and workpiece quality were examined. Finally, many of the commonly used wear tests used to analyze the wear resistance of tool coatings cannot be implemented for CVD diamond coatings due to their high hardness. An impact test was therefore constructed to allow the determination of the wear resistance of CVD diamond tools.     

Cr基金属氮化物涂层改善冷冲模性能的研究

采用非平衡磁控溅射法在硬度分别为56HRC和62HRC的Cr12MoV冷作模具钢表面制备Cr/CrN/CrTiAlN涂层,综合分析了涂层的表面性能,并进行了应用试验。实验结果和应用试验表明：Cr/CrN/CrTiAlN涂层能显著提高Cr12MoV钢基体的表面硬度（2550HV25）及承载能力,并与基体较好地结合,从而显著减少了Cr12MoV钢基体的磨粒磨损,耐磨性提高,对于高的基体硬度这一效果更为明显。经Cr/CrN/CrTiAlN涂层的翻边精整冷冲模,较未表面处理模具其使用寿命提高了两个数量级以上。     

球形碳化钨增强钴基堆焊涂层的组织及低温耐磨性

目的提升低温钢的摩擦磨损性能,为极地特殊船板的焊补和延寿技术提供试验依据。方法利用等离子转移弧技术,在低温钢E32表面堆焊制备3组球形不同碳化钨含量的钴基涂层,比较该改性涂层和E32钢在低温条件下(–20℃)的摩擦磨损性能。通过X射线衍射仪、扫描电子显微镜、能谱分析仪、3D光学轮廓仪等研究手段,分析碳化钨含量对堆焊层耐磨损性能和显微组织的影响规律,并揭示其耐磨损机理。结果在载荷为50 N、滑动速度为20 mm/s条件下,经2 h干滑动摩擦磨损后,3组涂层较低温钢E32的摩擦系数和体积磨损率均下降,磨痕的宽度和深度均变小。富含WC、W₂C增强相以及Cr₂₃C₆、Cr₇C₃、Co₆W₆C和Fe₆W₆C等碳化物硬质相的涂层,显著提升了E32钢的硬度和低温耐磨性。涂层的低温耐磨性能随着碳化钨含量的增大而提高,未添加碳化钨的涂层的主要磨损机理为磨粒磨损和粘着磨损,当碳化钨的质量分数为30%和60%时,主要磨损机理为三体磨粒磨损。结论通过在E32钢表面进行等离子转移弧堆焊,得到了结构致密、高硬度和抗低温耐磨性的球形碳化钨增强钴基表面改性涂层,在一定程度上提升了低温钢的服役寿命。     

Microstructure of electroplated hard chromium coatings after plasma nitrocarburizing

Plasma nitrocarburizing was carried out on the hard chromium coating deposited on SM45C mild carbon steel substrate by electroplating. After plasma nitrocarburizing at 720 °C for 20 h, a 6–7-μm-thick nitride layer consisting of CrN and Cr₂N was formed on the surface of Cr coating with the microhardness of about 950–1100 HV0.1. Due to the effect of annealing caused by plasma nitrocarburizing process at higher temperature and the Cr being a strong carbide-forming element, the carbon in steel substrate diffused outward into the Cr coating and reacted with Cr forming Cr carbide interface layer between the Cr electroplating and substrate. The nitrogen going into the microcracks and the volume increase accompanied by Cr nitride and carbide formation would cause the microcracks inherent to hard chromium plating disappear and improve its corrosion resistance. The microstructures of nitride and carbide layers were studied using X-ray diffraction and cross-sectional transmission electron microscopy.     

The study on the chip formation and wear behavior for drilling forged steel S48CS1V with TiAlN-coated gun drill

The solid carbide gun drill was coated with TiAlN, and a comprehensive evaluation on the wear behavior and chip formation had been performed on it for machining forged steel S48CS1V at a cutting speed of 12.66 mm/s (4400 rpm) with a continuous Minimum Quantity Lubrication (MQL). Cutting torque had been measured versus with the quantity of the machined crankshaft. The cutting torque curves revealed the three wear stages that were the initial stage, the semi-steady stage and the disastrous stage. Gun drill with TiAlN coating suffered from adhesive wear on the wear pad and chemical diffusion wear on flank face. Additionally, sliding wear and chipping were the wear forms. The high temperature and stress played the important roles in the adhesive and chemical diffusion wears. The high alternative stress produced the plastic deformation and cold welding for the atomic absorption and thus it made the grains of carbide substrate tearing-off from deforming cobalt bond, therefore adhesive wear took place.