CVD金属石膜刀具的制造技术及其应用

主要论述了CVD金刚石厚膜刀具制造过程中的几个关键工艺,包括切割、焊接、抛光和刃磨等,介绍了CVD金刚石膜刀具加工复合材料的实验研究。     

拉伸模具内孔CVD金刚石薄膜抛光工艺研究

化学气相沉积(CVD)金刚石一般无法直接应用,需要对其进行抛光处理。在熟悉平面厚膜抛光的机理基础上,采用自制抛光的设备,对拉伸模具内孔CVD金刚石薄膜进行机械抛光工艺的研究,借助表面粗糙度仪、扫描电子显微镜(SEM)对抛光前后及抛光过程中金刚石的表面形貌进行了观察,并对抛光过程进行了分析,研究表明:采用先粗抛光后半精抛光的工艺较为理想。     

CVD金刚石膜抛光新技术

提出了一种新的CVD金刚石膜抛光技术。金刚石膜表面被预先涂覆一层导电金属，然后采用电蚀方法对该表面进行加工，使金刚石膜突起的尖峰被迅速去除，加工中金刚石表面的石墨化使电蚀加工得以不断延续。采用CVD金刚石膜抛光新技术，可以高效率地完成对CVD金刚石膜的粗抛光。     

CVD金刚石厚膜焊接刀具的制造及切削性能

用于制造金属切削刀具的金刚石主要有四种类型：（1）天然单晶金刚石；（2）人工合成单晶金刚石；（3）聚晶金刚石复合片（PCD）；（4）化学气相沉积（CVD）金刚石膜。近年来，随着CVD金刚石工艺的发展，CVD金刚石对具的应用越来越广泛。CVD金刚石对具有两类：CVD金刚石薄膜涂层刀具和CVD金刚石厚膜焊接刀具。由于金刚石厚膜焊接刀具兼有单晶金刚石和金刚石薄膜涂层刀具的优点，从而具有广阔的应用前景。本文主要介绍金刚石厚膜的制备、厚膜刀具的制造及厚膜刀具的切削性能。     

CVD金刚石厚膜刀具切削性能的试验研究

分析了CVD金刚石厚膜刀具材料的性能特点 ,对CVD金刚石厚膜车刀进行了精密切削和难加工复合材料切削试验 ,结果表明 :CVD金刚石厚膜刀具加工铝合金的表面粗糙度可达Ra0 0 5 μm ;切削难加工复合材料时刀具耐磨性和使用寿命明显优于硬质合金刀具、PCBN刀具和PCD刀具     

CVD金刚石涂层拉伸模具内孔的抛光装置研制

在CVD金刚石膜抛光机理研究的基础上,采用模块化的设计思想,对抛光装置的模具装夹及传动模块、抛光头及传动模块、高频感应加热模块、抛光装置床身模块进行了设计,完成了CVD金刚石涂层拉伸模具内孔的抛光装置的研制。用此装置抛光在保证较高的抛光效率的同时可以获得较好的表面质量。     

气相沉积(CVD)金刚石厚膜与聚晶金刚石显微组织及其使用特性分析

经对PCD和CVD金刚石厚膜显微组织的研究，发现气相沉积法生产的金刚石厚膜与PCD有着完全不同的组织形式。研制刀具并进行切削性能试验，验证了CVD金刚石厚膜刀具与PCD刀具的切削适用范围，分析了它们在机械切削加工领域中的不同使用特性。     

PCD与CVD金刚石显微组织及使用特性分析

经对PCD与CVD金刚石厚膜显微组织的研究，发现气相沉积法生产的金刚石厚膜与PCD有着完全不同的组织形式。研制刀具并进行切削性能试验，验证了CVD金刚石厚膜刀具的切削适用范围，分析了它们在机械切削加工领域中的不同使用特性。     

导电CVD金刚石电极电火花精微加工研究

将导电CVD金刚石厚膜用作电火花加工的电极，研究了其精微加工特性。实验显示，导电CVD金刚石电极在窄脉宽精微加工条件下的损耗极低，几乎为零；且在某些条件下导电CVD金刚石电极的加工效率优于铜电极。研究结果初步表明导电CVD金刚石有着优异的电火花加工性能。     

CVD金刚石刀具的制备工艺研究

详细介绍了CVD金刚石厚膜刀具和涂层刀具的制备工艺，分析了目前制约CVD金刚石刀具制造和工业化过程的关键技术问题，制备出的CVD金刚石刀具满足了高硅铝合金等难加工材料的加工需求。     

Numerical analysis of Nd:YAG pulsed laser polishing CVD self-standing diamond film

Chemical vapor deposited(CVD) diamond film has broad application foreground in high-tech fields.But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications.Laser polishing is a useful method to smooth self-standing diamond film.At present,attentions have been focused on experimental research on laser polishing,but the revealing of theoretical model and the forecast of polishing process are vacant.The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory.The experimental investigation is also carried out on Nd:YAG pulsed laser smoothing diamond thick film.The simulation results have good accordance with the results of experimental results.The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd:YAG pulsed laser.The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields.The temperature at the peak of diamond film is much higher than that in the valley,which leads to the smoothing of diamond thick film.The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out.The results show that high power density laser makes the diamond surface rapid heating,evaporation and sublimation after its graphitization.It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle,moderate laser pulsed energy,large repetition rate and moderate laser pulse width.The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality.     

Failure Mechanisms of CVD Diamond Wafers and Thin Films During Polishing

This article investigates the failure mechanisms of CVD diamond wafers and thin films during a fast dynamic friction polishing process. To explore the evolution of temperature and stress fields, a comprehensive finite element analysis was systematically carried out, with the aid of experimental examination. It was found that the discontinuity and sharp change of the stresses across the film-substrate interface causes debonding failure of a CVD diamond thin film specimen. In the case of a CVD diamond wafer, however, the high surface tensile stress and bulk bending is responsible for the cracking. It was concluded that specimen cracking is sensitive to the polishing pressure, and that the polishing window for the CVD thin films is smaller. Polishing time is a critical factor, because a longer time corresponds to a higher thermal stress. This article points out that using the combination of a smaller polishing load and a greater sliding speed is a good option in selecting polishing parameters. To minimize cracking, a stepwise polishing process can be used. With the proper parameters obtained in this study, very smooth, high-quality surfaces of CVD diamond wafers and thin films can be produced in a short polishing duration of minutes.     

Prediction of the Interface Temperature Rise in Tribochemical Polishing of CVD Diamond

Tribochemcial polishing is one of the most efficient methods for polishing CVD (Chemical Vapor Deposition) diamond film due to the use of catalytic metal. However the difficulty to control the interface temperature during polishing process often results in low material removal because of the unstable contact process. So this research investigates the contact process in the tribochemical polishing of CVD diamond film and proposes a dynamic contact model for predicting the actual contact area, the actual contact pressure, and the interface temperature in the polishing process. This model has been verified by characterizing surface metrology of the CVD diamond with Talysurf CLI2000 3D Surface Topography and measuring the polishing temperature. The theoretical and experimental results shows that the height distribution of asperities on diamond film surface in the polishing process is well evaluated by combining the height distribution of original and polished asperities. The modeled surface asperity height distribution of diamond film agrees with the actual surface metrology in polishing process. The actual contact pressure is very large due to the small actual contact area. The predicted interface temperature can reach the catalytic reaction temperature between diamond and polishing plate when the lowest rotation speed and load are 10 000 r/min and 50 N, respectively, and diamond material is significantly removed. The model may provide effective process theory for tribochemcial polishing.     

CVD金刚石厚膜刀具的耐磨性试验

介绍了ＣＶＤ 金刚石刀具的特点,进行了ＣＶＤ 金刚石厚膜刀具与ＰＣＤ 刀具的耐磨性对比试验,结果表明ＣＶＤ 金刚石厚膜刀具的耐磨性明显优于ＰＣＤ 刀具,但韧性略低。     

CVD金刚石厚膜焊接刀具的试验研究

提出一种制作CVD金刚石厚膜焊接刀具的新工艺。采用电子辅助化学气相沉积法 (EACVD)制备直径10 0mm、厚度 0 8～ 1mm的金刚石厚膜 ;通过对金刚石刀头表面进行金属化处理 (化学气相沉积W膜 ) ,改善了金刚石的耐高温性及与低熔点合金焊料的浸润性 ,可在大气环境下实现金刚石刀头与刀架的焊接。车削试验结果表明 :用新工艺制作的金刚石刀具适用于精密加工     

FABRICATION OF DIAMOND TUBES IN BIAS-ENHANCED HOT-FILAMENT CHEMICAL VAPOR DEPOSITION SYSTEM

Deposition of diamond thin films on tungsten wire substrate with the gas mixture of ace- tone and hydrogen by using bias-enhanced hot filament chemical vapor deposition(CVD)with the tantalum wires being optimized arranged is investigated.The self-supported diamond tubes are ob- tained by etching away the tungsten substrates.The quality of the diamond film before and after the removal of substrates is observed by scanning electron microscope(SEM)and Raman spectrum.The results show that the cylindrical diamond tubes with good quality and uniform thickness are obtained on tungsten wires by using bias enhanced hot filament CVD.The compressive stress in diamond film formed during the deposition is released after the substrate etches away by mixture of H_2O_2 and NH_4 OH.There is no residual stress in diamond tube after substrate removal.