梯度功能陶瓷刀具材料的残余应力设计及制备

根据陶瓷刀具切割时刀楔内的应力分布规律及刀具损坏机理的分析,首次提出以陶瓷刀具材料的组成分布进行设计以及梯度的模型,通过对不同组成分布的刀具材料制备过程中的残余应力及刀具切削过程中的热应力,机械应力进行模拟,以残余应力与外加应力部分抵消为目标优化设计了梯度组成分布,按设计结果,采用粉末铺填－热压烧结工艺研制成功Ａｌ２Ｏ３／ＴｉＣ系梯度功能陶瓷刀具材料。     

利用人工神经网络方法开发Al2O3/TiN系复相陶瓷刀具材料

复相陶瓷刀具材料应用前景广阔。本文提出了利用人工神经网络方法辅助开发复相陶瓷刀具材料，基于BP算法，建立了预测颗粒增韧复相陶瓷刀具材料各组分体积百分含量的预测模型。实际开发了Al2O3/TiN系复相陶瓷刀具材料，材料的力学性能满足要求。     

陶瓷刀具材料及应用技术

陶瓷刀具具有优良的切削性能，在金属切削加工中越来越受到重视。本文对陶瓷刀具的种类、性能和应用进行了论述，并指出陶瓷刀具材料的发展方向。     

新型陶瓷刀具材料的研究与开发

工业用钢材的质量提高使材料加工难度增加,耐高温的高硬度高强度陶瓷材料被用做切削刀具并逐渐推广应用。本文对陶瓷刀具的材质、种类、性能特点作了比较和评价,并重点介绍了新型的晶须增韧陶瓷刀具。最后,对陶瓷刀具的市场前景进行了预测,并指出了陶瓷刀具研制方面应该深入研究的课题。     

两类陶瓷刀具的现状、性能与应用

综述了氧化铝系和氮化硅系两类陶瓷刀具的发展现状,阐述了两类陶瓷刀具的力学性能与切削性能,论述了两类陶瓷刀具的特点、加工范围以及合适的切削加工用量,提出了刀具使用过程中的一些注意问题。     

Al2O3—TiB2陶瓷刀具材料的研制及其耐磨性能研究

本文研制成功了一种新型陶瓷刀具材料即Al_2O_3-Ti B_2陶瓷刀具材料。文中讨论了该材料的研制方法,力学性能和微观结构特点,并对该材料的磨损行为和磨损机理进行了研究。结果表明:Ti B_2粒子的弥散可以明显提高该材料的耐磨性。加工淬火钢时该材料的抗磨损能力明显优于Al_2O_3-TiC陶瓷刀具材料。Al_2O_3-Ti B_2陶瓷刀具材料的磨损过程主要受粘着、耕犁和微破损机制的控制。     

Al2O3／SiCW陶瓷刀具材料中晶须的取向对其力学和切削性能的影响

Ａｌ２Ｏ３／ＳｉＣＷ陶瓷刀具材料由于热压过程的影响，造成晶须在基体中定向排布于垂直热压方向的平面上，因此不同方向的补强、增韧效果有所差异。本工作测量了Ａｌ２Ｏ３／ＳｉＣＷ陶瓷刀具材料不同方向上的断裂韧性和抗弯强度，分析了晶须的取向对该陶瓷刀具材料力学性能的影响。切削试验表明晶须的取向对晶须增韧陶瓷刀具材料的磨损和破损性能有较好的影响。根据切削加工过程中刀具的受力特点，提出了有利于切削加工的刀具前、     

浅析陶瓷刀具高速切削可靠性的影响因素

简要介绍了影响陶瓷刀具高速切削可靠性的几种因素，阐明了陶瓷刀具与被加工材料的匹配性要求和陶瓷刀具几何角度的选择，以充分发挥陶瓷刀具的工效高、使用寿命长和加工质量好等优点。     

技术创新助推新型陶瓷刀具在机加工中的应用优势凸显

随着新技术革命的发展,要求不断提高切削加工生产率和降低生产成本,特别是数控机床的发展,要求开发比硬质合金刀具切速更高、更耐磨的新型刀具。针对新型陶瓷切削刀具的应用前景广阔,分析了切削刀具材料的种类及其特点,研究了新型陶瓷切削刀具的性能突显,介绍了新型陶瓷切削刀具运用实例,提出了陶瓷切削刀具材料的研发应用方向。     

先进陶瓷刀具的材料及质量

陶瓷刀具由于其独特的性能而令世人瞩目，人们竟相开发新材料、新工艺来提高刀具的可靠性，降低刀具的成本。先进的陶瓷刀具材料将是二十一世纪最有希望、最有竞争力的刀具材料。     

Design and development of ceramic-based composites with tailored properties for cutting tool inserts

A successful approach to the development of tailored cutting tool materials requires the development of innovative concepts at each step of manufacturing, from the material design, synthesis of composite powders, to their processing and sintering. In this paper, a computational design approach is applied in the development of reinforced ceramic-based cutting tool inserts with tailored structural and thermal properties. Several potential filler materials are considered at the material design stage for the improvement of structural and thermal properties of a selected matrix material. Properties, such as an improved thermal conductivity and reduced coefficient of thermal expansion are essential for an effective cutting tool insert to absorb thermal shock at varying temperatures. In addition, structural properties such as elastic modulus have to be maintained within a moderate range. A mean-field homogenization theory and effective medium approximation using an in-house code are applied for predicting potential optimum structural and thermal properties for the required application. This is done by considering the effect of inclusions as a function of volume fraction and particle size in the ceramic base matrix. Single inclusion composites such as alumina-silicon (Al₂O₃-SiC) and alumina-cubic boron nitride (Al₂O₃-cBN) as well as hybrid composite such as alumina-silicon-cubic boron nitride (Al₂O₃-SiC-cBN) are developed using the Spark Plasma Sintering (SPS) process in line with the designed range of filler size and volume fraction to validate the computational results. It is found that the computational material design approach is precise enough in predicting the target properties of a designed hybrid composite material for cutting tool inserts.     

Effect of nano-scale texture pretreatment on wear resistance of WC/Co tools with/without TiAlN coated flank-face in dry turning of green Al2O3 ceramics

Advanced ceramics after sintering are almost processed by grinding or non-traditional machining. Nevertheless, these methods are limited by complexity of processing efficiency, tool wear and economic effectiveness. So machining green ceramics before sintering is introduced, it is environmentally friendly, efficient and cheap with high removal rate of materials. During dry turning green ceramics, flank-wear of tools and processing quality of compacts are two main elements to evaluate cutting performance of tools. The processing efficiency and economic effectiveness are mainly effected by the cutting performance of tools. In this paper, polished tool, tool with nano-scale textured flank-face, tool with TiAlN coating deposited on polished flank-face, and tool with TiAlN coating deposited on nano-scale textured flank-face were prepared. Effect of nano-scale texture pretreatment on wear-resistance of WC/Co tools with/without TiAlN coated flank-face was studied in turning of green Al₂O₃ ceramics. Results displayed that nano-scale textures on the flank-face had prominent effects on the enhancement of flank-wear resistance of tools. Relevant mechanisms were explored that nano-scale textures exhibited “derivative cutting” to protect unworn face from abrasion, and nano-scale textures pretreated on the flank-face could enhance the adhesion strength between coating and matrix. These developed tools could also significantly improve the processing quality of machined surfaces.     

硬质合金粉末表面涂层陶瓷的材料

利用溶胶－凝胶法在ＴｉＣ粉末,（Ｗ,Ｔｉ）粉末表面涂层Ａｌ２Ｏ３陶瓷,通过热压烧结制得了两种新型涂层的刀具材料（ＦＴＣ１和ＦＴＣ２）,粉末涂层材料ＦＴＣ１和ＦＴＣ２的力学性能满足刀具材料的使用要求。利用扫描电镜观察发现基体粉末表面较均匀地涂覆了一层α－Ａｌ２Ｏ３陶瓷,并对材料的力学性能和微观结构进行了分析。     

A numerical approach to the heat transfer in monolithic and SiC reinforced HfB2, ZrB2 and TiB2 ceramic cutting tools

Cutting tools are widely used in industry and must be hard enough for machining processes, which should work appropriately at low temperatures to improve cutting speed and productivity. In this research, a numerical method was employed to calculate the temperature distribution in the cutting tools made of different diborides. Monolithic and SiC reinforced HfB₂, ZrB₂ and TiB₂ ceramics were selected for investigation and comparison studies. In this regard, 3-dimensional heat conduction equation was solved in a cutting tool with radiative, convective and heat flux boundary conditions by finite element method using COMSOL Multiphysics. This study clarifies that the maximum temperature in the tools made of ZrB₂ and TiB₂ among the monolithic ceramics is lower than that of HfB₂. Moreover, the temperature variation slope versus time is the highest in HfB₂. All composite materials reinforced with SiC showed lower maximum temperature than the monolithic ones. The thermal performance of TiB₂–SiC and ZrB₂–SiC composites was acquired to be better than that of the other investigated materials. The dominant heat transfer mechanism in the cutting tools was conduction.     

Cutting characteristics of dental glass ceramics during in vitro dental abrasive adjusting using a high-speed electric handpiece

Machinability is an important characteristic of dental ceramics for restorative dentistry because machining is not only commonly employed in dental CAD/CAM systems but also essential in dental adjustments for occlusal fitting and restorative quality. This paper reports on an in vitro study on machinability of dental ceramics by quantifying cutting characteristics of feldspar and leucite glass ceramics in simulated dental adjusting using a high-speed electric handpiece and diamond burs. Cutting forces, force ratio, energy, surface integrity and bur topography were evaluated as functions of clinically relevant cutting conditions. The results indicate that tangential and normal forces and specific cutting energy for both materials exhibited significant dependences (p<0.01) on both the bur depth of cut and the bur feed rate. Surface roughness showed a weak influence by the choice of the material (0.05>p>0.01) but no correlations with the cutting conditions applied (p>0.05). At the slower feed rates or smaller depths of cut the cutting behaviors for the two materials were very similar in terms of cutting forces and specific cutting energy. At the deeper depths of cut or faster feed rates, normal forces for leucite glass ceramic were significantly higher than those for feldspar glass ceramic (p<0.01). However, leucite glass ceramic produced better cutting surfaces with less fracture areas compared with feldspar ceramic due to its lower index of brittleness and higher force threshold for brittle–ductile transition. This research provides a methodological qualification in evaluating cutting characteristics of dental ceramics and quality control in clinical dentistry.     

国内金刚石圆锯片近期发展现状与展望

金刚石圆锯片广泛应用在加工大理石、陶瓷、花岗岩等脆硬性材料中,是石材加工的重要工具,也是金刚石类工具中消耗量最大的加工工具。文章对金刚石圆锯片近期的发展做了总结,对金刚石圆锯片未来的重点发展领域进行了展望。     

A critical review on self-lubricating ceramic-composite cutting tools

Self-lubricating ceramic cutting tools have recently gained considerable attention as the tool wear in cutting hard-to-cut materials greatly affects the production cost, integrity of the machined surface, and productivity. In an attempt to compile the progress made in this important research area, a critical review has been performed covering a range of aspects. These include the current research trends and the need for self-lubricating ceramic tools, identification of prospective high-temperature solid lubricants and their limitations followed by a presentation of recent experimental and numerical work conducted related to self-lubricant ceramic cutting tools. Various lubrication mechanisms involved in the cutting process are also examined to identify general tribological response under various tribo-systems, which is expected to provide useful directions for the researchers and cutting industry. The current and emerging synthesis techniques are discussed in detail and compared with respect to ceramic cutting tools. Finally, some research gaps and future directions are suggested that could lead to optimum design and development of innovative self-lubricating ceramic tools.     

Hole surface morphology and tool wear mechanisms during cutting 3D carbon/carbon composites using diamond core drill

Carbon fiber reinforced carbon matrix (carbon/carbon) composites are a new class of ceramic engineering materials and applied in aerospace structures due to high strength in non-oxidizing atmospheres at extremely high temperatures, while it is a typical difficult-to-machine material due to its anisotropy and heterogeneity. Defects such as burrs, tears and fiber pullout are likely to be produced on machined surface when inappropriate machining parameters are employed. The material removal mechanisms during mechanical cutting of carbon/carbon composites are still not fully understood. In this work, the three-dimensional braided carbon/carbon composite was employed, hole surface morphology and tool wear mechanisms during drilling with a bronze sintered diamond core tool were studied. Result showed that fiber tearing and burrs were mainly observed at hole entrance and exit under low level of feed speed down to 20 mm/min. When the feed speed increased to 40 mm/min and 60 mm/min, severe tearing, uncut fibers, and delamination appeared at hole exit. Fiber orientation showed significant influence on material removal mechanisms as well as fiber shearing/bending fracture, fiber pullout and matrix fragmentation. The ground, pullout and fracture of abrasive particles were the main tool wear mechanisms, cutting chips were attached and blocked inside the core drill probably due to high cutting temperature in dry condition, as the temperature increased to ～260 °C under the feed speed of 60 mm/min.     

Cutting performance of microwave-sintered sub-crystal Al2O3/SiC ceramic tool in dry cutting of hardened steel

Tool life and failure mechanisms of a microwave-sintered sub-crystal Al₂O₃/SiC ceramic tool (AS) in dry turning hardened steel were studied. The AS tool with plane face shows better cutting performance and wear resistance than the commercial ceramic tool SW500 and cemented carbide tool YG8 at both low and high cutting speeds. It's suitable for dry cutting at high speed (210–270 m/min), the cutting distance is 5–8 times longer than that of other two tools. The results indicate that the ceramic tool fabricated by this pressureless sintering technology can satisfy the requirements of high-speed machining. Wear forms of AS tool at low cutting speed are slight crater wear and groove wear, which were mainly caused by abrasion. At high cutting speed, tool failure forms are cater wear, groove wear and slight chipping caused by severe abrasion and adhesion.