气相沉积碳化钛工艺及涂层硬质合金刀片性能的研究

本文对化学气相沉积TiC的工艺、涂层硬质合金组织及性能作了较系统的阐述。对研究的诸问题,如各工艺参数(H_2、CH_4、TiCl_4、沉积温度、沉积室压力等)对沉积速率的影响;涂层成份与性能;涂层和基体之间脱碳层产生的原因、对涂层刀片性能的影响及减少脱碳层的方法;TiC涂层刀片的切削性能等,都得出了相应的有益结果。这为深入进行该项新工艺试验研究,为TiC涂层硬质合金刀片尽早生产使用,提供了一定条件。     

涂层弹性模量对配气凸轮应力分布影响研究

研究了涂层对凸轮接触应力分布的影响。通过有限元仿真的方法,为涂层赋予不同弹性模量的属性,对凸轮的应力分布进行分析。结果表明,涂层能有效的减小凸轮基体表面的应力,但涂层过大的弹性模量会使导致涂层与基体的材料失配。     

耐超高温喷管的材料选择

以要求承受从燃烧室喷出 2 50 0℃～ 310 0℃的高速燃气喷管为研究对象 ,采用难熔金属作为基体材料 ,并在其表面上实施陶瓷隔热涂层方案 ,对其所用材料进行了详细分析。     

激光涂层多冲碰撞疲劳强度的正交分析

对激光涂层零件进行多冲碰撞疲劳试验,并用正交方法对试验数据进行了分析。发现涂层材料对激光涂层的多冲疲劳强度起主要作用,基体材料次之。涂层厚度对疲劳强度的影响随循环次数的增加而减小。     

硬质合金涂层的新方法

涂层硬质合金刀具具有高的硬度、耐磨性,耐热性和抗月牙洼磨损能力,并能降低刀具与工件间的摩擦系数,具有很高的耐用度。此外,因它的通用性广,一种牌号的涂层硬质合金刀片常可胜任几个等级的未涂层刀片的切削工作,从而简化了刀具的管理。所以,近年来硬质合金刀具,特别是可转位刀片,涂层刀具的应用日益普遍。通常采用TiN(氮化钛)做硬质合金的涂层材料。众所周知,硬质合金TiN涂层一般都采用CVD(化学气相沉积)法,但因此法的沉积温度高,约1000℃左右,所以在涂层与硬质合金基体之间容易形成一层脆性的脱碳层,导致刀片脆性脱断,降低刀具的使用寿命。近年来的研究表明,只要正确掌握涂层工艺,PVD(物理气相沉积)法     

铝基体喷涂Al2O3-TiO2/NiCoCrAlY系梯度涂层的抗热震性能

在ZL104铝合金基体上喷涂了Al2O3-TiO2／NiCoCrAlY系梯度涂层和Al2O3-TiO2非梯度涂层,对这两种试样进行了室温←→400℃冷热循环试验,以研究涂层的抗热震性能和热震失效机制。结果表明：Al2O3-45%TiO2与基体热膨胀系数的差异所产生的热应力是热震过程中涂层剥落的主要原因,涂层成分的梯度变化缓解了热应力,提高了抗热震失效能力;在热震循环过程中试样的弯曲是由基体和涂层材料膨胀系数、导热系数的差异以及铝基体的塑性变形造成的,这种变形使涂层产生残余拉应力,降低了涂层的抗热震性能。     

热喷涂烧结涂层结合性能评价界面应力有限元分析

通过梯度液相烧结或中温反应烧结处理，热喷涂层具有很高的结合强度。采用线切割沿涂层／基体界面切成对称切口，两边黏结后直接拉伸的实验方法对此高强涂层抗拉结合强度进行评价。对应不同涂层材料和切口结构工艺参数，借助有限单元法对涂层／基体交界面上的应力分布及切口附近的应力集中进行了分析，为正确评价涂层／基体的结合强度提供了依据。     

高结合性能涂层与基体界面结合强度测定模型的有限元模拟

采用有限元法对高强结合性能涂层与基体界面结合强度进行了力学模拟,通过对涂层与基体界面最大法向应力和最大剪切应力的分析,比较了模型中有无金属加强板,不同的锥度、结合面宽度、涂层厚度对界面结合强度的影响,从而确定了最佳模型：使模拟过程中最大剪切应力明显降低,能够更好地体现不同体系法向应力的变化,并在最佳模型下研究了不同涂层和基体材料相互作用的界面结合强度。     

HOVF WC-10Co4Cr涂层磨削瞬态温度场及应力场数值模拟

从经典热传导方程和热弹塑性力学出发,建立了磨削过程中移动热源作用超音速火焰喷涂WC-10Co4Cr涂层材料的二维传热模型和热应力模型;在考虑材料热物理参数随温度变化的基础上,利用有限元分析软件ANSYS来研究双层材料在磨削热-结构耦合作用下的瞬时温度场和应力场。数值研究结果表明,由于WC-10Co4Cr涂层热传导系数和比热容比300M钢基体大,所以温升主要停留在涂层内;磨削温度沿工件深度方向非连续分布,涂层基体结合面的温度梯度最大;由于涂层、基体材料热膨胀系数差异较大,在结合面处产生极大的热应力;磨削温度、涂层-基体结合面热应力随涂层厚度的降低而增大。开展了磨削温度测量实验,测量了不同涂层厚度时工件表面的磨削温度,对数值仿真结果进行了验证。     

TiAl合金表面NiCrAlY涂层的抗高温氧化性能

采用多弧离子镀技术在γ-TiAl合金表面制备了NiCrAlY涂层,用SEM、EDS和XRD等分析了涂层在高温氧化前后的形貌、结构和物相组成,用恒温氧化方法测试了涂层与基体的氧化动力学曲线。结果表明:涂层在高温下可形成保护性氧化膜,使其抗氧化性能显著提升;在650~950℃氧化时,镍和钛元素发生互扩散,850℃时,涂层与基体之间形成了扩散带和齿状TiNi相,950℃时,互扩散现象加剧,涂层表面生成了TiO2,涂层氯化膜与基体间形成了Kirkendall孔洞,对其抗高温氧化性能不利。     

PCVD直流脉冲沉积温度对TiN／TiSiN复合涂层高温氧化性能的影响

采用工业用直流脉冲等离子体增强化学气相沉积（PCVD）法在硬质合金刀具材料上制备了TiN／TiSiN复合涂层。对比研究了TiN及不同温度制备的TiN／TiSiN复合涂层高温抗氧化性能。研究表明：含有非晶阻隔抗氧化结构si3N。的TiN／TiSiN复合涂层高温氧化性能远高于TiN涂层,TiN／TiSiN复合涂层提高到800℃,仍可避免出现较大面积氧化及脱落;PCVD直流脉冲沉积制备温度对涂层高温抗氧化能力有重要影响,550℃沉积制备的致密、均匀、颗粒小的复合涂层高温氧化性能最佳,600℃次之,500％最差。     

硬质合金基体预处理工艺对CVD金刚石涂层附着性能的影响

采用热丝CVD法通过不同基体处理工艺在YG8和YG6硬质合金基体上沉积了金刚石涂层,考察了基体表面预处理工艺对基体表面形貌、残留钴含量以及涂层结合力的影响。实验结果表明,一步法酸刻蚀的最佳作用时间为15min左右,无论采用一步法还是二步法,处理后的YG8硬质合金基体表面残留钴均已大幅降低至3%左右,而二步法处理后YG6基体表面钴含量仅为0.66%。通过压痕实验对比分析得出,一步法酸处理15min后的硬质合金基体上沉积的金刚石涂层压痕较小,其最大压痕尺寸为145μm,两步法处理硬质合金基体金刚石涂层压痕面积最小,表现出良好的附着性能。     

工艺参数对磁控溅射碳化锆薄膜的微结构与力学性能影响

采用碳化锆靶通过磁控溅射方法制备一系列碳化锆薄膜,采用XRD、SEM、AFM和微力学探针研究溅射气压和基于温度对碳化锆薄膜的微结构和力学性能的影响.结果表明:低溅射气压下,薄膜呈现结品良好的柱状品结构,其硬度和弹性模量分别为30.1GPa、256GPa.溅射气压提高到2.0Pa以上后,薄膜的柱状晶结构受到破坏,品粒减小...     

TiN/TiSiN复合涂层显微结构与力学性能研究

采用工业用直流脉冲等离子体增强化学气相沉积(PCVD)法在硬质合金刀具基体上制备了TiN和TiN/TiSiN复合涂层.对TiN涂层和不同沉积温度下制备的三种TiN/TiSiN复合涂层的微观结构和力学性能进行了对比研究.结果表明:随着沉积温度的升高,TiN/TiSiN复合涂层的结合力增大;沉积温度为550℃时,TiN/T...     

Mechanical and tribological properties of vapour deposited low friction coatings on Ni plated substrates

Soft steel and aluminium substrates with load-carrying layers of electroplated nickel were coated with commercially available low friction vapour deposited coatings. The mechanical and tribological properties of the coating and substrate composites were evaluated with special emphasis on the influence of the nickel layer. Two different thicknesses of the intermediate load-carrying nickel layer were tested. The samples were evaluated regarding friction and sliding wear, abrasive wear, hardness and elastic modulus, morphology and coating thickness and adhesion between substrate and coating. It was found that all the evaluated low friction coatings were possible to be successfully deposited on the intermediate nickel layer. A relatively thick intermediate nickel layer is a promising candidate for improvement of the load-carrying capacity.     

Load-carrying capacity evaluation of coating/substrate systems for hydrogen-free and hydrogenated diamond-like carbon films

Diamond-like carbon (DLC) coatings have shown excellent tribological properties in laboratory tests. The coatings have also been introduced to several practical applications. However, the functional reliability of the coatings is often weakened by adhesion and load-carrying capacity related problems. In this study the load-carrying capacity of the coating/substrate system has been evaluated. The DLC coatings were deposited on stainless steel, alumina and cemented carbide with two different deposition techniques: the tetrahedral amorphous carbon (ta-C) coatings were deposited by a pulsed vacuum arc discharge deposition method and the hydrogenated carbon (a-C:H) films by radio frequency (r.f.) plasma deposition method. The load-carrying capacity of the coated systems was evaluated using a scratch test, Rockwell C-indentation test and ball-on-disc test. The effect of substrate material, substrate hardness, coating type and coating thickness was studied. An increase in substrate hardness increased the load-carrying capacity for the coated systems, as expected. The two coating types exhibited different performance under load due to their different physical and mechanical properties. For the load-carrying capacity evaluations the ball-on-disc configuration was found to be most suitable. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tribological behaviour of W‐alloyed carbon‐based coatings in dry and lubricated sliding contact

Carbon‐based coatings with different W contents were deposited by direct current magnetron sputtering in reactive and non‐reactive atmospheres. All deposited coatings have compact morphologies with amorphous (tungsten‐free) or nanocrystalline structures (tungsten‐doped). The latter one was indicated by very broad peaks in X‐ray Diffraction spectra in the position of tungsten carbide suggesting W‐carbide nanoparticles embedded in an amorphous carbon matrix. The hardness increased from 10 to 15 GPa with increasing W content. The coatings were tribological tested at dry and lubricated conditions with increasing temperature in a coating/steel configuration. In dry sliding, the friction coefficient increases with the increase of the temperature reaching values higher than 1.0. The friction is significantly lower in lubricated contact using three different oils: poly‐alpha‐olefin, paraffin and olive oil. The olive oil shows promising lubricating properties at the temperature lower than 70°C; however, at higher temperature, the coatings were quickly worn through. Copyright © 2014 John Wiley & Sons, Ltd.     

Tribological properties of composite multilayer coating

Abstract

The use of surface coatings is emerging as one of the most important approaches in reducing friction and wear in various tribological applications. Even though single layer coatings have a wide range of applications, the performance of the single layer alone may not always be adequate to meet the desired tribological property requirements. Hence, coatings consisting of multilayers to meet different property requirements in demanding applications are required. In this study, the tribological properties of a graded composite multilayer coating, with a specific layer sequence of MoS₂/Ti–MoS₂/TiBN–TiBN–TiB₂–Ti deposited on tool steel substrate, have been investigated at temperatures of 40 and 400°C respectively. The experimental results from the tests at 40°C have shown that the friction coefficient value ranges between 0·02 and 0·034. It was found that the deposition parameters influenced the friction and durability of the coatings. Higher substrate bias was found to result in higher friction, and the coating deposited at high substrate bias and low N₂ flow showed the lowest durability. The friction coefficient and durability of the coatings were found to be highly dependent on temperature. At high temperature, the friction coefficient increases almost threefold, and the durability decreases significantly.     

ZrN涂层刀具的滑动磨损特性研究

山东大学摘要:采用电弧离子镀法在硬质合金刀具表面制备了厚度为2.19~5.23μm的ZrN系列涂层,测定了涂层的显微硬度,并通过划痕试验和摩擦磨损试验考察了涂层与基体的结合强度及其摩擦磨损性能。在扫描电镜下观察磨损表面形貌,结果表明:ZrN系列涂层能够显著提高硬质合金刀具的表面硬度;涂层与基体的结合强度较高,划痕临界载荷高于60N;与此同时,电弧离子镀法ZrN系列涂层可以显著改善硬质合金刀具的耐磨性能。磨损机理主要是磨粒磨损和涂层的微剥落。     

宽带激光熔覆高硬度火焰喷涂层组织和裂纹行为

对镍基合金火焰喷涂层进行宽带激光熔覆试验,分析熔覆层组织、物相组成和硬度分布规律以及工艺参数对组织、结合强度和硬度的影响。激光熔覆过程骤冷骤热的特点使得熔覆层内存在较高的拉应力,同时,由于激光熔覆镍基合金火焰喷涂层主要由g (Fe, Ni) 固溶体和弥散分布的高硬度脆性碳化物相(Ni, B) 和(Cr, Si) 相组成,熔覆层强度和硬度显著提高而延性降低,在凝固过程残余内应力的作用下极易开裂,熔覆层裂纹为低延性穿晶脆性冷裂纹。基体的预热和熔覆后保温缓冷可有效降低温度梯度,释放残余内应力,当预热温度为300 ℃时,熔覆层裂纹消失。