机械法抛光加工金刚石膜研究

在平面研磨机上使用金刚石抛光盘对金刚石膜进行了抛光实验。通过观察金刚石膜机械抛光过程中表面形貌的变化，并结合拉曼光谱分析，提出了金刚石抛光盘抛光金刚石膜的抛光机理主要是微切削和压力破碎作用，同时还可能有少量金刚石转变为非晶碳的作用。通过单因素实验研究，发现金刚石盘的粒度对抛光金刚石膜材料去除率的影响最为显著。转速越高，表面粗糙度越小，压力和粒度存在最优值，超过该值后，表面粗糙度并不会随之降低。     

文摘

20 0 10 30大面积ＣＶＤ金刚石膜的热铁板抛光 [刊 ,中 ]/刘敬明 ,蒋政 ,等∥北京科技大学学报 ,2 0 0 1,2 3(1) :43～ 45研制成功国内第 1台大面积ＣＶＤ金刚石膜热铁板抛光机。它可以在 10 -3 Ｐａ真空条件下 ,加热到 110 0℃ ;抛光台可以在 0～ 10ｒ/ｍｉｎ间实现无线调速 ,一次完成 3片Φ110ｍｍ的金刚石膜的抛光。金刚石膜在 980℃ ,2ｈ抛光的结果表明 ,该装置有良好的抛光效果。金刚石膜在 980℃抛光不同时间的Ｒａｍａｎ谱表明 ,金刚石热铁板抛光是金刚石石墨化和Ｃ原子不断扩散的过程。图 6参 62 0 0 10 31色谱法分离纯化富勒烯的研…     

陶瓷抛光砖用磨具(二)

４陶瓷抛光线用金刚石磨具的种类和特点４．１陶瓷磨具的分类 由于瓷质砖属于硬脆性非金属材料，其莫氏硬度已达６～８级，用一般磨具已很难进行高效大切削量的切削加工，只能使用金刚石工具。这种磨具目前绝大多数厂家以热压法生产刀头，然后焊接于钢基体上而成。根据使用功能分为：金刚石滚筒（或金刚石滚筒铣刀）；金刚石行星轮、圆柱轮；金刚石磨边轮；金刚石倒角轮。根据不同的设备，同一类产品在安装结构和尺寸上各不相同。４．２金刚石滚筒 金刚石滚筒由若干条金刚石螺旋纹组成，用于抛光过程的第一阶段。通过连续强力切削作用将砖坯…     

金刚石抛光用镍钨合金镀层的电镀制备工艺

采用脉冲电镀的方法快速制备耐磨损的超厚镍钨合金镀层，用以摩擦化学抛光金刚石，以实现金刚石的快速去除。采用正交实验研究了脉冲频率、平均电流密度、占空比对镀层组分、显微硬度、内应力和沉积速率的影响。最终在脉冲频率200 Hz、平均电流密度9 A/dm2和占空比0.8的条件下制备了显微硬度472.76 HV、内应力80.11 MPa、厚度为0.35 mm的镍钨合金镀层。经金刚石摩擦化学抛光实验验证，制备的镍钨合金抛光盘具有优异的抛光性能，相较于铸铁抛光盘，镍钨合金抛光盘具有更高的金刚石去除率（0.71μm/min）、更低的磨损量（0.16 g）和磨削比（94.25）。     

金刚石丸片与固结磨料抛光垫研磨硅片的比较研究

采用金刚石丸片和固结磨料抛光垫两种方式研磨加工硅片,以硅片的材料去除率(MRR)和表面粗糙度(Sa)为指标对金刚石丸片和固结磨料抛光垫的研磨性能进行了评价.结果表明:固结磨料抛光垫研磨硅片的材料去除率高于金刚石丸片;研磨后硅片的表面粗糙度也优于金刚石丸片,且表面粗糙度(Sa)在中部和边缘相差不大.最后分析了研磨硅片的产物-磨屑的形状特征,得出固结磨料抛光垫研磨硅片时的塑性去除量远高于金刚石丸片.     

Φ3.5mm金刚石串珠绳的锯切工艺研究

通过不同结构的设备,研究小直径金刚石串珠绳的切割效果,分析了水流对小直径金刚石串珠绳的切割效果,切割过程小直径金刚石串珠绳的弯曲量和切割面积的关系,以及不同线速度下金刚石被抛光的量及主要抛光面的抛光机理。     

上海交大CVD膜技术应用进展

上海交通大学把CVD金刚石薄膜制备技术应用于拉拔模具，不仅攻克了涂层均匀涂覆、附着力等关键技术，而且解决了金刚石涂层抛光这一国际性难题，就此他们申请了“大孔径金刚石涂层拉拔模的制备方法”等5项国家发明专利，其中3项已获得了授权。     

金刚石表面织构化处理技术（上）

在单晶工业金刚石的应用中，金刚石微粉常用作研磨和抛光材料，配制成研磨液或研磨膏，其颗粒尺寸为微米级和次微米级，粒径小于37微米。在光学工业中常用于镜头、镜片、光透射窗等元件的研磨和抛光加工；在电子工业中则用于蓝宝石、碳化硅、氮化镓、砷化镓等高级晶片的研磨抛光，一般均要求达到表面无划痕的光洁度。随着高科技的发展，在宇航工业和空间技术应用的超精光学元件如高清晰度摄像镜头、超高倍放大镜、远红外探测器、激光器等都要求有更高的表面光洁度。     

铝合金轮毂抛光技术现状

轮毂抛光是露骨电镀或涂装前的必要工序,抛光之后获得平整、光顺的表面。综述了轮毂抛光的技术难点,方法和特点,以及抛光过程中的工艺不足,对轮毂抛光工艺的进一步发展进行了展望,为开展轮毂抛光的研究和生产提供了一定的指导。     

等离子体刻蚀金刚石膜的研究方法及现状

等离子体刻蚀是金刚石膜的抛光、切割和图形化等加工过程中一项很重要的技术。本文综述了国内外等离子体刻蚀金刚石膜的研究成果。     

Investigation on the etching of thick diamond film and etching as a pretreatment for mechanical polishing

Etching with oxygen plasma produced by DC glow discharge was investigated as a potential technique for etching of diamond films and as a pretreatment technique for mechanical polishing of thick diamond films. The influence of DC power and gas pressure to etched morphology and etching rate were studied using scanning electron microscopy and electronic micro-balance, respectively. The electron temperature and plasma density were measured by Langmuir single probe to explicate the influence mechanism of etching parameters according to an etching model. The effect of etching on mechanical polishing was studied through surface roughness measuring instrument and Raman spectrometer.It was found that at a constant gas pressure the rise of DC power would result in the increase of deepening etch pits overspreading from the protuberant facet to the boundary of diamond crystallites with rising etching rate. And the same tendency was engendered by reducing gas pressure when the DC power remained. The numerous etch pits can be ascribed to etching with a higher rate of dislocations whose edges exist at the film surface. In accordance with an etching model, the measured results of Langmuir probe suggest that the main influence mechanism of etching are the plasma density and electron temperature, and the increase of etching rate and deepening etch pits can be mainly attributed to the enhanced directional etching with rising ion flux and sheath voltage. Appropriate etching with oxygen plasma is an effective pretreatment method for enhancing the efficiency of rough polishing process in mechanical polishing of thick diamond film.     

A comparison of mechanical lapping versus chemical-assisted mechanical polishing and planarization of chemical vapor deposited (CVD) diamond

Polishing and planarization of CVD diamond substrates are essential steps in the processing of synthetic diamond for applications in the semiconductor industry. Using the methods of mechanical lapping and chemical-assisted mechanical polishing (CAMP), CVD diamond samples were polished against a cast-iron scaife and an alumina plate, respectively, using the same pressure on the samples. A diamond slurry was used in the mechanical lapping process, and a heated liquid chemical was used in a patented chemical-assisted mechanical polishing and planarization (CAMPP) process. The diamond samples were analyzed at several time intervals during the lapping and polishing processes, and during a combination of the two processes in which mechanical lapping preceded CAMPP. The polishing rate and surface characteristics of the diamond samples were the primary analytical measurements made, and the data were used to compare the relative lapping/polishing efficiencies of the two processes in an effort to develop an optimized process for producing highly polished CVD diamond substrates.     

Evaluation research of polishing methods for large area diamond films produced by chemical vapor deposition

The current study compared several polishing techniques of chemical vapor deposition (CVD) diamond films. Although research on various diamond polishing techniques has been carried for years, some issues still need to be examined in order to facilitate application on large areas in a cost-efficient manner. In the present work, microwave plasma enhanced chemical vapor deposition (CVD) was used to obtain diamond films with full width half magnitude (FWHM) less than 10 wavenumbers at 1332 cm^− 1 Raman peak. The diamond films were processed through mechanical polishing, chemical-assisted mechanical polishing, thermo-chemical polishing, excimer laser ablation, and catalytic reaction assisted grinding. A profilometer, an atomic force microscope, and a scanning electron microscope have been used to evaluate the surface morphology of diamond films before and after polishing. The results obtained by using the above mentioned techniques were analyzed and compared.     

A new elegant technique for polishing CVD diamond films

It is well known that the columnar growth nature of CVD diamond results in a very rough growth surface and the surface roughness steeply increases with film thickness, especially for thick CVD diamond films. In this paper, we report the successful implementation of a new elegant technique for polishing thick polycrystalline CVD diamond films at high polishing rate of up to 10 μm/h. This technique involves polishing the as-grown polycrystalline diamond films with another thick as-grown polycrystalline diamond film, which acts as a polishing abrasive. Two types of diamond films were prepared using microwave plasma CVD and then polished for 2 h using the new polishing technique. A stylus profilometer, scanning electron microscopy and Fourier transform infrared spectroscopy were used to measure the surface roughness, characterize morphology and optical transmission of the samples before and after polishing, respectively. By polishing, thickness of 20–30 μm was removed from the top surface, and the mean surface roughness R_a of the films reduced significantly, e.g. for one film R_a reduced initially from 5.2 to 1.35 μm and the other from 3.2 to 0.55 μm. The principal advantages of this new polishing technique are simplicity, flexibility and time saving. This simple method can serve as ‘rough chipping’ to quickly remove the rough top surface and then combine with conventional polishing methods for precision machining to further reduce the surface roughness to a specific desired degree.     

High-quality homoepitaxial diamond (100) films grown under high-rate growth condition

We present advantages of high-power microwave plasma chemical vapor deposition (MPCVD) in homoepitaxial diamond film deposition. Diamond films grown at comparatively high growth rate of 3.5 μm/h showed intense free-exciton recombination emission at room temperature. The free-exciton decay time of the diamond film at room temperature, 22 ns, was much longer than that of type-IIa single crystal, indicating electronically high quality of the homoepitaxial films. Dislocation-related emissions were locally observed, a part of which created by mechanical polishing process was successfully removed by surface etching process using oxygen plasma. Another advantage of the high-power MPCVD is effective impurity doping; boron-doped diamond films with high carrier mobility and high carrier concentration were reproducibly deposited. An ultraviolet photodetector fabricated using the high-quality undoped diamond film showed lower noise equivalent power as well as higher photoresponsivity for ultraviolet light with better visible-blind property, compared to those of standard Si-based photodetectors. The high-power MPCVD is, thus, indispensable technique for depositing high quality diamond films for electronic devices.     

Diamond polishing

The empirical know-how of single crystalline diamond polishing has been developed over centuries in the diamond gem cutting industry. Since the 1950s new and varied uses and potential applications for synthetically produced diamond have been consistently proposed and developed. This innovation process continues with the availability of ever better, more specialized and less costly single crystalline and polycrystalline diamond materials. Yet, the potential exploitation of this hardest of materials is still in its infancy. Polishing is a critical and limiting step for advancing diamond applications in terms of cost effective processing and the achievable material surface finish. The current state-of-the-art of polishing single crystalline and polycrystalline diamond materials is reviewed based on the published literature. The material removal process during traditional mechanical polishing using diamond grit and polishing wheels is strongly anisotropic and depends upon crystal planes and polishing directions. Wear debris analyses and molecular dynamic simulations led to the understanding that this anisotropy is primarily caused by a mechanically induced transition from diamond to an amorphous carbon phase rather than by microchipping as previously thought. Mechanical polishing also leads to subsurface damage and limits the achievable surface finish for single crystalline diamond. Advanced techniques are discussed to improve the polished crystal's surface quality. Mechanical polishing of polycrystalline diamond films and freestanding plates is particularly slow due to the intrinsic structure variations in such materials. To overcome these limitations faster polishing techniques have been developed and are reviewed and compared. These techniques introduce additional chemical and physical means of material removal extending the capabilities of mechanical polishing. There is no single method that can address all requirements, but the available variety affords the careful selection of an optimal process for a given task. Finally, while diamond polishing is a subject of interest since centuries, it still remains a very important research area required to unfold the promise of diamond as a technical material.     

High-rate ultrasonic polishing of polycrystalline diamond films

We report on fast polishing of polycrystalline CVD diamond films by ultrasonic machining in a slurry with diamond particles. The material removal mechanism is based on diamond micro-chipping by the bombarding diamond particles subjected to action of an ultrasonic radiator. The treated samples were characterized with optical profilometry, SEM, AFM and micro-Raman spectroscopy. The developed method demonstrates the polishing rate higher than those known for mechanical or thermo-mechanical polishing, particularly, the surface roughness of 0.5 mm thick film can be reduced in a static regime from initial value Ra ≈ 5 μm to Ra ≈ 0.5 μm for the processing time as short as 5 min. No appearance of amorphous carbon on the lapped surface was revealed, however, formation of defects in a sub-surface layer of a few microns thickness was deduced using Raman spectroscopy. The polishing of a moving workpiece confirmed the possibility to treat large-area diamond films.     

Diamond surfaces polished both mechanically and manually; an atomic force microscopy (AFM) study

Diamond surfaces that are polished both mechanically and manually have been studied using atomic force microscopy and compared with optical micrographs obtained within the Nomarski interference mode. The extra gentle manual polishing which follows the mechanical polishing was developed to produce much smoother, well characterized and flat diamond surfaces than those prepared through mechanical polishing only. Both the AFM and optical micrographs showed the manually polished diamond surfaces being smoother and also exhibiting lower roughness parameters than those polished mechanically only. Annealing the surfaces to 250 °C did not show any noticeable changes in the surface roughnesses, but a 750 °C vacuum-anneal did show some differences that were attributed to possible surface etching through the desorption of the surface-bonded species.     

Pretreatment of substrate surface for improved adhesion of diamond films on hard metal cutting tools

The d.c. plasma jet CVD process is one of the most promising coating processes used for the production of polycrystalline diamond films. In comparison with other CVD processes, its obtainable linear growth rates, in the range of 100 μm/h, are much higher than growth rates of microwave or hot filament CVD (1–10 μm/h).

One interesting application is the diamond coating of cutting tools. The main problem here is the poor adhesion of the films. Therefore, a mechanical or chemical pretreatment or intermediate layers are used to improve the adhesion.

In these investigations the influence of mechanical pretreatment by grinding and polishing with diamond powder of different grain sizes as well as chemical etching are examined on WC-Co hardmetals. Sputtered metallic interlayers of different thicknesses and arc-ion plated amorphous carbon films are deposited on these substrates, and diamond films were synthesized on these pretreated cutting tools by d.c. plasma jet CVD.

Adhesion and wear resistance of the diamond films have been examined by dry turning tests on very abrasive metal-matrix composites. Distinct improvement in adhesion of diamond coatings on hard metal substrates was achieved by two methods of substrate surface pretreatment: etching with Murakami's solution and following ultrasonically seeding with diamond particles or using an amorphous carbon film as intermediate layer.     

Fracture strength and toughness of chemical-vapor-deposited polycrystalline diamond films

The strength of diamond films prepared by chemical vapor deposition (CVD) is usually much lower than that of natural-type IIa single-crystal diamonds. In this work, the fracture strength of free-standing diamond films deposited by direct current arc plasma jet CVD has been examined by conducting three-point bending experiments. The results obtained for both the polished and as-grown samples were in good agreement with a well-known Hall–Petch equation describing the relationship between the fracture strength and grain size, indicating that grain refinement represented an effective way of improving the mechanical properties of CVD diamond films. Furthermore, the diversification of the crystalline texture of the films achieved by polishing apparently increased their fracture strength, which was inversely proportional to the film thickness. A theoretical method for estimating the fracture strength of free-standing CVD diamond films by approximating their intrinsic strength was proposed, whereas their fracture toughness was determined by conducting simplified four-point bending tests at room temperature, 25?°C, using a single-edge pre-cracked beam method.