TiN涂层的性能及其对冷挤压模寿命的影响

在冷挤压模上进行ＴｉＮ 涂层处理,并对涂层进行Ｘ－射线衍射分析,测量了涂层的表面硬度、滑动摩擦系数和低能量冲击磨损性能。结果表明：涂层良好的耐磨性大大提高了冷挤压模的使用寿命。     

HA／ZrO2功能梯度涂层中羟基磷灰石的超微结构分析

利用净能量控制的PRAXAIR 4500型等离子喷涂系统，在钛合金基体上制备出HA／ZrO2功能梯度涂层，采用HTEM、XRD、SEM和表面轮廓仪等对涂层表面HA的显微结构和相结构特征进行分析。结果表明：（1）喷涂态涂层表面HA主要以非晶相存在，存在微量的纳米HA晶体；（2）大气气氛700℃晶化处理显著提高涂层表面HA结晶度，涂层以结晶的HA相存在，且晶体结构完整；（3）HA／ZrO2功能梯度涂层表面粗糙多孔，呈现“二级窝洞”的形貌特征，有利于材料与骨组织间的结合。     

Ti(C,N)基金属陶瓷功能梯度材料的制备

利用热等静压技术高温高压的特点,在金属陶瓷的基体上获得了硬质梯度涂层.借助扫描电镜、X射线衍射仪、显微硬度计和电子探针分析技术对N化后材料的组织、结构、性能进行了测试分析.结果表明,高温高压N化能在表面形成硬质梯度薄膜,表面区域N的活度梯度是促使各合金元素迁移形成氮化表面层特征组织的最终驱动力.表面硬度和心部韧性提高,并且硬度由表及里逐渐减小,这是由于高温高压氮化处理使材料中的孔洞闭合,微裂纹和缺陷的减少使得材料的性能得到显著提高.     

钛合金表面磁控溅射制备HA/YSZ梯度涂层

采用射频磁控溅射法在Ti6Al4V基体上制备了HA/YSZ生物梯度涂层.借助于XRD,SEM,EDS等对溅射涂层的相组成、微观形貌和界面状态进行了研究.实验结果表明:磁控溅射的生物梯度涂层呈非晶态,经过退火处理,可以使其转化为晶态,恢复缺失的OH-1;梯度涂层的微观表面凹凸不平,并呈现网状结构和较多的孔隙,后处理仍保持梯度涂层利于新骨生长的表面形貌,并使其转变为针状结晶.HA/YSZ梯度涂层与基体结合紧密,在涂层与基体界面结合处约5.0μm范围内存在Ti,Ca,P,Zr的相互扩散层,梯度涂层与基体的界面结合强度达60.5MPa.     

H13模具钢的应用及发展

介绍了H13钢的化学成分及特性。详尽论述了H13钢应用于热锻模、热挤压模和有色金属压铸模的现况。阐述了H13钢常规的淬火回火热处理工艺制度。从表面低温化学热处理、高能束表面处理和复合处理三个方面及微舍金化方面叙述了H13钢的最新研究动态。     

C-Si 梯度涂层对碳纤维性能的影响

本文提出并探索了在碳纤维表面化学气相沉积 C-Si 梯度涂层的新方法,研究了 C-Si 梯度涂层对碳纤维性能的影响。实验结果表明,碳纤维表面化学气相沉积 C-Si 梯度涂层结构中的 C,Si 元素均呈非晶态结构;梯度涂层能大幅度提高碳纤维的抗氧化性。梯度涂层减少了涂层与纤维基体的各种不匹配因素,缓和了涂层中热应力,限制了氧化反应的进行,使梯度涂层纤维氧化前后强度均明显高于 Si,SiC,SiO_2等单一涂层纤维。     

稀土活性梯度生物陶瓷涂层的组织结构研究

文章采用宽带激光熔覆技术在TC4钛合金上制备了含羟基磷灰石活性相的生物陶瓷复合涂层。利用晶相显微镜、显微硬度计分析手段对复合涂层的组织、硬度进行了研究,采用MG63人成骨细胞与材料共培养的方法,对梯度活性陶瓷涂层进行了细胞形态实验。结果表明,稀土梯度生物活性陶瓷涂层界面结合良好,显微硬度较大,且涂层表面细胞生长旺盛、形态正常,细胞相容性更好。     

等离子熔射制备梯度功能材料技术

梯度功能材料是一种具有特殊结构和特点的新材料,对该材料的深入研究有助于提升和改造传统的材料产业.应用等离子熔射技术制作了梯度功能材料,对梯度成分进行了设计分析,同时测试了梯度涂层的金相组织以及显微硬度.结果表明梯度功能材料比传统的单一材料以及复层材料使用性能和寿命大大提高.功能梯度材料应用于现代制造业以及对材料表面进行改性将对我国工业技术的发展产生重大影响.     

热喷涂技术制造特种功能涂层

采用热喷涂技术进行涂层材料、涂层结构的复合设计，将结构与性能完全不同的材料有机地组合在一起，可研制出性能优越且多种功能并存的新型涂层。如：水润济状态下的运动摩擦副表面抗蚀、耐磨、减摩陶瓷涂层；新一代纳米氧化皓高温热障涂层；抗高温隔热烧蚀梯度复合结构涂层；高温管道表面阻尼减振降噪、隔热复合涂层以及高温热辐射涂层等。研究表明：表面工程技术对传统材料进行表面改性并能赋予其新的特种功能是完全可行的。     

仿生磷灰石涂层与钛基体结合强度的划痕法实验

本文采用碱热处理及SBF浸泡的方法在钛片上制备了仿生磷灰石涂层,并采用AES进行表面成分-深度分析,划痕法测定磷灰石涂层与基体的结合强度.结果显示,经碱热处理而制得的钛表面仿生磷灰石涂层与基体结合的界面为成分梯度界面,二者的结合要通过成分含量呈梯度变化的过渡层:Ca、P元素的含量从表面到基体逐渐下降,Ti元素的含量逐渐上升.热处理有利于提高涂层的基体结合强度,其原因是热处理使SBF中形成的磷灰石的晶核细小而均匀,使得表面涂层与基体之间的结合更为紧密.预钙化处理后形成的磷灰石涂层与金属之间仍为成分梯度界面,因此对涂层的基体结合强度影响不大.     

Residual/thermal stresses in FGM and laminated thermal barrier coatings

The plane strain elasticity problem for a functionally gradient material (FGM) and a multi-layered homogeneous coating bonded to a metal substrate due to a uniform temperature change is considered. The substrate is assumed to be a nickel-based alloy-Rene-41. The FGM coating is a particulate composite of Rene-41 and zirconia with volume fractions continuously varying through the thickness. The multi-layered coating consists of one, two or four homogeneous layers with stepwise changing volume fractions. With a possible failure mechanism of surface cracking or edge debonding in mind, the relevant stresses on the surface of the coating and along the interfaces are evaluated. For the piecewise homogeneous coating the power of singularity and the corresponding stress intensity factors at the points of intersection of the interfaces and the free ends are calculated. It is shown that by using the FGM coating the stress singularities are eliminated and the stress distribution is smoothed considerably. Sample results for the displacements and for the contour plots of an effective stress governing the yield behavior of the material are given and the asymptotic behavior of the stress state around the singular point is examined.     

Verschleißreduzierung an Matrizen für das Präzisionsschmieden von Zahnrädern durch Mehrlagenhartstoffbeschichtung (TiN‐TiCN‐TiC)

Wear reduction on dies for precision forging of gear wheels by means of multi‐layer coating (TiN‐TiCN‐TiC) Due to high thermal, mechanical and tribological loads the tool life quantity of hot forging dies compared to other manufacturing processes is relatively low. Depending on the number of forged parts the mentioned loads lead to different failure causes of the dies. In this connection wear is the main failure cause of hot forging dies. Especially in the precision forging process of gear wheels with its exacting tolerances the tool life quantity is low, which leads to often interruptions of the production process. Because wear concentrates on the near‐surface die areas, these problems can be reduced by increasing the wear resistance of these areas by the Duplex PACVD‐Method, which means nitriding and multi‐layer coating (TiN‐TiCN‐TiC).     

铸钢基体双金属梯度连接制备大型锻模的新方法研究进展

为解决大型模锻液压机(8万t压机)锻模采用传统制造方法时,遇到的模块自由锻难度大、锻透性差、热处理硬度低、制造成本高等问题,提出了铸钢基体双金属梯度连接制备大型锻模的新方法。该方法可节省传统锻模制造方法中自由锻工序、粗加工工序、锻后热处理工序及模具钢材料成本,虽然增加了双金属梯度层连接材料及相应工序,但仍然可以大幅降低锻模制造成本,成本可节约20%~40%,制造周期可缩短30%~40%,模具寿命可提高40%~50%。铸钢基体双金属梯度连接制备大型锻模方法,从根本上解决了大型锻模的制造和成本难题,是大型锻模制造革命性的新方法,具有广泛的应用前景和重大的经济效益。     

基于类等势场的粉末高温合金盘件预成形设计

根据能量最小原理和最小阻力原理,利用塑性变形过程中坯料的流动规律与静电场等势线分布类似这一特性,提出一种能够进行预成形设计的新方法——类等势场法,并采用该方法对粉末高温合金盘件进行预成形设计,从中优选出6组预成形形状,利用MSC/Super Form商用有限元软件对上述预制坯的等温成形过程进行了数值模拟,得到了6组粉末高温合金盘件在预锻到终锻过程中的应力率参数和应变率梯度.通过对盘件轮毂、辐板和轮缘3个部位6个典型单元体应力率参数g的比较与分析,以及整体盘件应变率梯度的比较,并参考预锻变形量和终锻变形量,认为选择3号预锻模为最佳方案.     

Interface cracking between functionally graded coatings and a substrate under antiplane shear

Coating technology plays a significant role in a number of applications such as high temperatures, corrosion, oxidation, wear, and interface. In this paper, we investigate the interface cracking between ceramic and/or functionally graded coatings (FGM coatings) and a substrate under antiplane shear. Four coating models are considered, namely single layered homogeneous coating, double layered piece-wise homogeneous coating, single layered FGM coating and double layered coating with an FGM bottom coat. Mode III stress intensity factors (SIFs) are calculated for the different coating models. In the case of μ_L > μ₀ where μ₀ is the shear modulus of the substrate and μ_L the shear modulus of the material at the surface of the coating, it is found that the single layered FGM coating reduces SIF slightly, whereas the coating system with a top homogeneous layer and a thin FGM bottom layer reduces SIF significantly. In the case of μ_L < μ₀ the SIF is found to be larger for the FGM coatings than for the homogeneous coatings. The FGM coating, however, may still be superior to homogeneous coatings in this case as FGM coatings usually provide better bonding strength between the coating and substrate. Finally, the applicability of the SIF concept in the fracture of FGM coatings is discussed. Large modulus gradients in thin coatings may seriously restrict the application of SIFs as the SIF-dominant zone may fall into the crack tip nonlinear deformation and damage zone. The same argument exists for some interphase models in interface crack solutions.     

Structural changes of radial forging die surface during service under thermo-mechanical fatigue

Radial forging is one of the modern open die forging techniques and has a wide application in producing machine parts. During operation at high temperatures, severe temperature change associated with mechanical loads and the resultant wearing of the die surface lead to intense variation in strain on the die surface. Therefore, under this operating condition, thermo-mechanical fatigue (TMF) occurs on the surface of the radial forging die. TMF decreases the life of the die severely. In the present research, different layers were deposited on a 1.2714 steel die by SMAW and GTAW, with a weld wire of UDIMET 520. The microstructure of the radial forging die surface was investigated during welding and service using an optical microscope and scanning electron microscope. The results revealed that, after welding, the structure of the radial forging die surface includes the γ matrix with a homogeneous distribution of fine semi-spherical carbides. The weld structure consisted mostly of columnar dendrites with low grain boundaries. Also, microstructural investigation of the die surface during operation showed that the weld structure of the die surface has remained without any considerable change. Only dendrites were deformed and broken. Moreover, grain boundaries of the dendrites were revealed during service.     

高轮毂齿轮毛坯的模锻成形工艺及模具设计

通过对高轮轮毂齿轮的结构进行分析,制定出该锻件锻造成形的工艺流程,阐述了模锻工步、型腔的设计及模锻操作方法,实现了在3150t热模锻压力机上锻造生产。     

Three-dimensional analysis of a functionally graded coating/substrate system of finite thickness

The concept of functionally graded material (FGM) is currently actively explored in coating design for the purpose of eliminating the mismatch of thermomechanical properties at the interfaces and thus increasing the resistance of coatings to functional failure. In the present paper, three-dimensional elastic deformation of a functionally graded coating/substrate system of finite thickness subjected to mechanical loading is investigated. A comparative study of FGM versus homogeneous coating is conducted to examine the effect of the coating type on stress and displacement fields in the system.     

喷油器体锻模优化设计

目的以喷油器体模锻成形为研究对象,对锻模结构与尺寸进行分析和优化设计。方法通过优化锻模设计(尤其是优化锁扣、终锻模膛、飞边槽、钳口、滚挤模膛等结构与尺寸设计以及根据滚挤模膛高度尺寸优选原材料下料规格),克服原锻模设计的缺点。结果有效改善了喷油器体的模锻工艺性,减小了难变形区,减小了变形力,减少了原材料消耗0.15 kg/件,提高了合格品率,提高了锻造效率(减少打击次数3~5锤次/件),提高了锻模使用寿命至少1倍,以及降低了锻模与锻件成本等。结论最终获得的喷油器体锻模,结构高紧凑又强度足够,使用性能优越,可为类似锻模设计和实际生产提供了有力的参考依据。