陶瓷刀具材料切削加工G4335V高强钢时的耐磨性能研究

本文对Ａｌ２Ｏ３／ＴｉＣ陶瓷刀具材料切削加工Ｇ４３３５Ｖ高强钢时的切削性能和耐磨性进行了试验研究。结果表明：在低速切削条件下，Ａｌ２Ｏ３／ＴｉＣ陶瓷刀具和硬质合金刀具（ＹＴ１５）的抗后面磨损能力相差不大，而在高速切削条件下，前者的抗后面磨损能力远高于后者。Ａｌ２Ｏ３／ＴｉＣ陶瓷刀具前面的磨损形式主要为粘结磨损，后面的磨损形式主要为磨粒磨损。     

A12O3／TiC梯度功能陶瓷刀具的切削性能及损坏机理

采用粉末叠层填充一轴向热压烧结工艺研制成功性能优良的Ａ１２Ｏ３／ＴｉＣ梯度功能陶瓷刀具,并在柴油机排气阀外圆粗车工序中与普通陶瓷刀具ＬＴ５５进行了对比切削试验,结果表明,Ａ１２Ｏ３／ＴｉＣ梯度功能陶瓷刀具的寿命比ＬＴ５５提高５０％。梯度功能陶瓷刀具的破损主要是机械疲劳作用所致,而ＬＴ５５刀具的破损主要是扫劳作用的结果。     

Al2O3—TiB2陶瓷刀具材料的研制和应用

本文讨论了Ａｌ２Ｏ３－ＴｉＢ２陶瓷刀具材料ＬＰ１的制备，物理机械性能和微观结构特点。并用切削试验数据表明，这种刀具材料的耐磨性明显优于正在广泛使用的Ａｌ２Ｏ３－ＴｉＣ陶瓷刀具材料。     

先进陶瓷刀具材料的破损性能

研究了稀土补强Ａｌ２Ｏ３／（Ｗ,Ｔｉ）Ｃ陶瓷刀具材料的破损性能,发现在断续切削淬硬４５钢时,该刀具材料具有较镐的抗破损性能,其抗破损性能比相应不含稀土的Ａｌ２Ｏ３／（Ｗ,Ｔｉ）Ｃ陶瓷刀具材料提高约２０％,在不同的切削条件下,疲劳裂纹和热裂纹是造成刀具材料失效的主要原因。     

Al_2O_3－TiC系陶瓷的组织结构和性能

Ａｌ２Ｏ３－ＴｉＣ系陶瓷由Ａｌ２Ｏ３、ＴｉＣ和金属粘结相组成。陶瓷组织为骨架结构相互穿插结合。其颗粒大小为０．５０～１．０μｍ，在ＴｉＣ颗粒内存有细微亚结构，它的尺寸为０．１０～０．２０μｍ。Ａｌ２Ｏ３－ＴｉＣ界面结合紧密．但不完全匹配。该陶瓷材料硬度为２４ＧＰａ和９３．７０ＨＲＡ。根据压痕法测得的有关参数，计算所得ＫＩＣ值为５．８６ＭＰａ·ｍ１／２。文中讨论了克服该系陶瓷脆性和提高其韧性的途径。该陶瓷已广泛用于制造切削刀具。     

刀具材料的回顾与展望（下）

３．陶瓷陶瓷刀具材料分为３类：１）氧化铝基陶瓷　一般在Ａｌ２Ｏ３基体中加入ＴｉＣ、ＷＣ、ＳｉＣ、ＴａＣ、ＺｒＯ２等成分,经热压制成复合陶瓷。硬度达ＨＲＡ９３～９５,抗弯强度达０．７～０．９ＧＰａ。为提高韧性,常添加少量的Ｃｏ、Ｎｉ等金属。２）氮化硅基陶瓷　常用的是Ｓｉ３Ｎ４＋ＴｉＣ＋Ｃｏ的氮化硅基复合陶瓷,其韧性常高于Ａｌ２Ｏ３基陶瓷,硬度相当。３）复合氮化硅—氧化铝陶瓷　其化学成分为Ｓｉ３Ｎ４７７％,Ａｌ２Ｏ３１３％,Ｙ２Ｏ３１０％,硬度可达ＨＶ１８００,抗弯强度可达１．２０ＧＰａ。这种陶瓷…     

新型陶瓷刀具LD－1的切削性能

对新型陶瓷刀具ＬＤ－１切削超高强度钢和淬硬钢时的切削性能作了试验研究，结果表明，ＬＤ－１刀具较其它Ａｌ２Ｏ３－ＴｉＣ系陶瓷刀具更适于断续切削加工，因而具有较大的推广应用价值。     

特殊添加剂陶瓷刀具材料的研制和应用

实验研究了特殊添加剂陶瓷刀具材料的制备、力学性能和微观结构特征。试验结果表明：该材料的抗破损性能明显优于其他Ａｌ２Ｏ３－ＴｉＣ陶瓷刀具材料。     

新型陶瓷刀具LD—1的切削性能

对新型陶瓷刀具ＬＤ－１切削超高强度钢和淬硬钢时的切削性能作了试验研究，结果表明，ＬＤ－１刀具较其它Ａｌ２Ｏ３－ＴｉＣ系陶瓷刀具更适于断续切削加工，因而具有较大的推广应用价值。     

复合氮化硅陶瓷刀具切削性能的试验研究和应用

简要介绍了“Ｓｉ３Ｎ４－ＴｉＣ－Ｃｏ”多元系新型氮化硅基复合陶瓷刀具的切削性能及其应用情况。切削试验和生产应用证明它是一种有优良切削性能、值得推广的陶瓷刀具。     

陶瓷涂层刀具切削灰铸铁的试验研究

为了探究陶瓷涂层刀具涂层材质、基体材质对切削性能的影响,试验采用四种陶瓷涂层刀具连续干切削灰铸铁,测试了切削力和切削温度的变化情况以及后刀面的磨损量和已加工表面的粗糙度。结果表明,在刀具基体同为Si_3N_4的条件下,涂层材质为Ti N/Al_2O_3/Ti C的刀具比Ti N/Al_2O_3的切削性能好;在涂层材质同为Ti N的条件下,刀具基体Al_2O_3/Ti CN比Al_2O_3/Ti C的切削性能好。研究发现:四种陶瓷涂层刀具前刀面磨损形式均为微崩刃和月牙洼,后刀面磨损形式均为磨粒磨损和粘着磨损,涂层的磨损形式均为剥落和扩散磨损。     

MULTI-SCALE AND MULTI-PHASE NANOCOMPOSITE CERAMIC TOOLS AND CUTTING PERFORMANCE

An advanced ceramic cutting tool material Al2O3/TiC/TiN (LTN) is developed by incorporation and dispersion of micro-scale TiC particle and nano-scale TiN particle in alumina matrix. With the optimal dispersing and fabricating technology, this multi-scale and multi-phase nanocomposite ceramic tool material can get both higher flexural strength and fracture toughness than that of Al2O3/TiC (LT) ceramic tool material without nano-scale TiN particle, especially the fracture toughness can reach to 7.8 MPa·m0.5. The nano-scale TiN can lead to the grain fining effect and promote the sintering process to get a higher density. The coexisting transgranular and intergranular fracture mode induced by micro-scale TiC and nano-scale TiN, and the homogeneous and densified microstructure can result in a remarkable strengthening and toughening effect. The cutting performance and wear mechanisms of the advanced multi-scale and multi-phase nanocomposite ceramic cutting tool are researched.     

Al2O3/TiC/CaF2自润滑陶瓷刀具切削过程中的减摩机理

在Al2O3/TiC陶瓷刀具基体内加入固体润滑剂CaF2来改善其摩擦学特性,制备出Al2O3/TiC/CaF2自润滑陶瓷刀具.以该陶瓷刀具对45钢进行干切削试验,结果表明添加固体润滑剂的Al2O3/TiC/CaF2自润滑刀具的摩擦因数比未添加固体润滑剂的Al2O3/TiC陶瓷刀具显著降低,表现出了良好的减摩效果.在切削过程中,Al2O3/TiC/CaF2自润滑陶瓷刀具中的固体润滑剂由于受到摩擦和挤压作用而析出,能在刀具前刀面上形成润滑膜,可阻止刀-屑间的粘着,显著降低前刀面与切屑间的平均摩擦因数.对自润滑陶瓷刀具切削后磨损表面显微分析表明,前刀面在切削过程中形成了自润滑膜的生成、破损、脱落和再生的循环过程.因此,Al2O3/TiC/CaF2自润滑陶瓷刀具在其整个生命周期内始终具有润滑效果.     

一种Al2O3基陶瓷刀具的切削性能研究

采用热压工艺制备了一种Al2O3／Ti（CN）陶瓷刀具材料,对其进行了切削性能试验,分析了其切削磨损机理并比较了三种陶瓷刀具的切削性能。试验结果表明,在切削淬硬45^#钢和铸铁时,Al2O3／Ti（CN）陶瓷刀具的耐磨性与Al2O3／TiC陶瓷刀具接近,但明显高于Al2O3／TiC／CaF2自润滑陶瓷刀具;Al2O3／Ti（CN）陶瓷刀具的后刀面磨损量随切削速度和背吃刀量的增加而增大。SEM分析发现,在切削淬硬45^#钢和铸铁时Al2O3／Ti（CN）陶瓷刀具后刀面主要磨损形式为磨粒磨损。     

Cutting performance of Si<Subscript>3</Subscript>N<Subscript>4</Subscript>/TiC micro-nanocomposite ceramic tool in dry machining of hardened steel

A type of Si₃N₄/TiC micro-nanocomposite ceramic cutting tool material was fabricated using Si₃N₄ micro-matrix with Si₃N₄ and TiC nanoparticles. Cutting performance of the Si₃N₄/TiC ceramic cutting tool in dry cutting of hardened steel was investigated in comparison with a commercial Sialon insert. Hard turning experiments were carried out at three different cutting speeds, namely 97, 114, and 156 m/min. Feed rate (f) and depth of cut (a _p) were fixed at 0.1 mm/rev and 0.2 mm, respectively. Results showed that cutting temperature increased rapidly to nearly 1000 °C with increasing cutting speed. The two types of cutting tools featured similar wear behavior. However, the Si₃N₄/TiC micro-nanocomposite ceramic cutting tool exhibited better wear resistance than the Sialon tool. Morphologies of crater and flank wear were observed with a scanning electron microscope. Results indicated that wear variation of the two types of ceramic cutting tools differed in the same conditions. Wear of the Si₃N₄/TiC micro-nanocomposite ceramic cutting tool is mainly dominated by abrasion and adhesion, whereas that of the Sialon ceramic cutting tool is dominated by abrasion, adhesion, thermal shock cracking, and flaking.     

添加固体润滑剂的自润滑陶瓷刀具材料及其减摩机理研究

采用热压工艺制备Al2O3/TiC/CaF2(ATF)自润滑陶瓷刀具材料,考察其室温下的机械性能,并通过切削性能试验分析其切削减摩机理。结果表明:添加固体润滑剂对陶瓷材料的机械性能有一定影响,其中CaF2含量为10%的Al2O3/TiC/CaF2陶瓷材料的力学性能最好,强度和硬度最高,分别达到了589MPa和HV15·4GPa,可以用作刀具材料;ATF自润滑陶瓷刀具在切削过程中,减摩性能优于LT55陶瓷刀具,能够在前刀面形成一层较完整的固体润滑膜,膜的存在使得ATF自润滑刀具材料具有一定的减摩能力,而后刀面具有磨粒磨损的特征,由于磨粒的刻划作用而没有形成较完整的润滑膜。     

Wear behavior of some cutting tool materials in hard turning of HSS

This study presents an assessment of the performance of four cutting tool in the machining of medium hardened HSS: polycrystalline c-BN (c-BN+TiN), TiN coated polycrystalline c-BN (c-BN+TiN), ceramic mixed alumina (Al₂O₃+TiC), and coated tungsten carbide (TiN coated over a multilayer coating (TiC/TiCN/Al₂O₃)). The Al₂O₃+TiC and the coated carbide tools can outperform both types of c-BN at high cutting speeds. Raman and SEM mapping revealed an alumina tribo-layer that protects the surface of the Al₂O₃+TiC cutting tool. The high chemical and thermal stability of Al₂O₃ tribo-films protects the tool substrate because it prevents the heat generated at the tool/chip interface from entering the tool core.     

Optimum design of cam-roller follower mechanism using a new evolutionary algorithm

Selection of tooling to perform specific operations like drilling and milling on ceramic materials using rotary ultrasonic machining process is an important aspect to meet stringent dimensions on workpiece as well as intended performance of tool. This phenomenon is more critical for micro rotary ultrasonic machining. In the present study, an effort was made to do micro drilling operation of Ø0.3 mm tool with varying geometry, having different wall thicknesses and abrasive grain sizes using design of experiments. The effect of tool-based parameters like grain size and wall thickness has been studied on axial cutting force, radial cutting force, tool wear, edge chipping area and taper. After examining axial and radial cutting forces, it has been concluded that lower wall thickness (80 μm) tool is good for drilling operation; and higher wall thickness (100 μm) tool is good for milling operation under same material removal rate conditions. It has been also investigated that lower wall thickness (80 μm) tool has less edge chipping area and less taper and can impart high drilling depth as compared to higher wall thickness (100 and 150 μm) tool. It is also concluded that lesser grain size (15 μm) tools are advantageous in terms of edge chipping area and cutting force for drilling and milling operations as compared to higher grain size (30, 35 and 45 μm) tool at constant material removal rate. Higher grain size tools have been broken at 1.13 mm³/h material removal rate conditions due to bad profile accuracy. But higher grain size tools have worked fairly well at less material removal rate condition. Higher grain size tools produced less wear. Tool wear was found minimum in higher wall thickness (100 μm) tool having higher abrasive grain size (30 μm). Using inferred results, Ø0.3 mm drilling experiments have been carried out on six aerospace ceramic materials. Also, groove of 0.5 mm size using Ø0.3 mm optimised tool has been successfully carried out in sintered SiC.     

Carbide tool wear mechanism in turning of Inconel 718 superalloy

Wear surfaces of the cutting tools are analyzed to study the wear mechanism of cemented carbide tools in turning in Inconel 718 superalloys. SEM and EPMA analyses indicated that the wear of carbide tools during high speed turning condition (V = 35 m min⁻¹) was caused by diffusion of elements (Ni or Fe) in workpiece into tool's binder (Co) by a grain boundary diffusion mechanism. This action weakened the bonding strength between carbide particles (WC, TiC, TaC) and the binder (Co). The carbide particles were then detached out of the cemented carbide tool by high flow stresses. The proposed grain boundary diffusion mechanism is also confirmed by theoretical analysis.