Single Diamond Grain Research Articles

Experimental Investigation of Microcutting Mechanisms in Granite Grinding

This paper shows the results of investigations performed in the brittle materials microcutting at the Faculty of Mechanical Engineering, Belgrade University. The interactions between a single diamond grain and the machined granite are analyzed. The change in the normal cutting force as a function of grain penetration speed and depth was experimentally established in microcutting of two types of granite originating from Serbia. Based on the grain traces on granite and the generated cracks, the critical grain penetration depth for the formation of brittle fracturing was established. The experiments are intended to assist in the optimization of the grinding process as technology dominant in the granite finishing.

Experimental Investigation of Microcutting Mechanisms in Marble Grinding

This paper offers an experimental study of the microcutting mechanisms in marble grinding to aid the optimization of the marble grinding process. The necessity for investigating these mechanisms is dictated by the increased use of marble in many applications and the fact that grinding and polishing processes are the dominant technologies used to meet surface finish requirements in this natural material. The experiments are aimed at the determination of the normal component of the cutting force and of the grain traces in microcutting with a single diamond grain. The investigations carried out make provisions for establishing critical grain penetration and cutting depths and allow the prediction of the normal cutting force component as a function of grain penetration speed and depth.

Development of CNT-Coated Diamond Grains Using Self-Assembly Techniques for Improving Electroplated Diamond Tools

Single crystalline diamond grains covered by nested carbon nanotubes (CNTs) were constructed using self-assembly techniques. The acid-treated CNTs (MWCNTs-COOH) are first adsorbed onto amine-terminated diamond grains, which were chemically functionalized by silane coupling treatments, in N, N-dimethylformamide solution. Then, the drying and readsorption cycle deposited CNT coatings on the diamond grains due to CNT-CNT interactions caused by van der Waals forces. When the diamond grains were bonded to steel substrates by electroplating using nickel sulfamate plating bath, the bonding strength of the CNT-coated diamond grains to the Ni matrix was almost twice as large as that of the normal diamond grains. Hence, the CNT-coated diamond grains are very useful for improving the tool life of electroplated diamond tools.

Adaptive control of diamond drilling of nonmetallic materials

The basic principles for selecting the work regimes for diamond drilling of nonmetallic materials are presented. The process of microcutting by a single diamond grain is examined, and relations between the components of the cutting force and the ratio of the rate of the main motion to the feed rate are obtained on the basis of known relationships. It is shown that adaptive control of the drilling nonmetallic materials is possible using two-circuit systems — one for feed-rate control and one for cutting-rate.

Development of Solid-Type Diamond Rotary Dresser Utilizing CVD Diamond Disc - Application to Low-Speed Dresser -

A solid-type diamond rotary dresser consisting of a CVD diamond disc is developed and applied to the dressing of a vitrified CBN grinding quill for internal grinding. This dresser has a feature not found in the other discrete-type rotary dressers used thus far, in which it continuously contacts the grinding wheel and leaves a spiral on the grinding wheel surface. The solid-type diamond rotary dresser was mounted on a low-speed spindle supported by journal bearings, and its dressing performance was compared with those of two discrete-type rotary diamond dressers: a dressing roll on which surface single diamond grains are brazed and a dressing roll made of a metal-bonded diamond wheel. It is found that the solid-type diamond rotary dresser tends to bring about rough grinding conditions among the three dressers.

A comparative study of p-type diamond films using Raman and transport measurements

The influence of deposition temperature in the properties of synthetic diamond films grown by two different chemical vapor deposition (CVD) techniques, hot-filament- and microwave-plasma-assisted, was investigated. These samples were obtained using the optimal growth conditions previously achieved in this work. Raman spectroscopy was employed in order to investigate the diamond film quality as a function of the deposition temperature. It was found that the nondiamond carbon bands decrease as the deposition temperature increases for both the deposition methods, leading to higher-quality diamond films. The micro- and macro-Raman spectra showed that the nondiamond band is already present in a single diamond grain. Both techniques provided well homogeneous diamond films and with equivalently good quality. Boron-doped diamond films with different carrier concentration levels were also studied. In order to get details about the electrical properties of the films, resistivity as a function of the boron concentration—in association with Raman spectra—and temperature-dependent transport measurements were employed. The results showed that the boron doping is the main responsible for the conductivity and that the variable range hopping (VRH) mechanism dominates the transport in these doped diamond films.

Point defects as result of surface deformation on a GaAs wafer

Scratches on the surface of an undoped semi-insulating GaAs wafer have been produced by a wedge-shaped single diamond grain. The subsurface damage has been analyzed by a positron microprobe. This instrument provides laterally resolved positron annihilation measurements, which are sensitive to lattice defects like vacancies and dislocations. We can clearly identify different regions of damage which have been characterized both by conventional scanning electron microscopy and the positron microbeam. The latter reveals indications of plastic deformation due to the trace of created defects observed. We discuss the possible implications of the observed ductile behavior of GaAs usually known to be brittle at room temperature and under atmospheric pressure.

Micro-IL and micro-PIXE studies of rich diamond meteorites at Legnaro nuclear microprobe

A combination of micro-ionoluminescence (micro-IL) and micro-PIXE was used to characterize diamond grains inside a type of meteorites known as ureilites. Ureilites are a group of achondrites unique in containing relatively large amounts of carbon occurring as diamond, graphite or lonsdaleite. A shock origin for ureilitic diamonds has been widely accepted though an exact knowledge of the conditions during high-pressure graphite conversion is not yet achieved. Micro-IL is a very powerful technique for material investigation and particularly for diamond analysis. Using this technique we were able to identify the occurrence of the diamond phase inside carbon meteoritic inclusions and to perform micro-PIXE analysis on single diamond grains. In fact, IL in low nitrogen content diamonds is dominated by A-band emission (centered at about 2.9 eV) and so, considering only IL monochromatic map at such a spectral band, it was possible to identify them. By making measurements directly on the meteorites, contamination during chemical extraction processes was avoided and it was possible to study not only the diamond phase, but also its distribution inside carbon inclusions.

Study on Nano-machining Process Using Mechanism of a Friction Force Microscope. 1st Report. Trial Production of Nano-machining and Measurement System Modified a FFM.

In order to control the process of the nanometer-scale machining precisely, it is necessary to understand the change of mechanism in nanometer-scale removing process. In this point of view, a unique nano-machining and measurement system, which utilizes the mechanisms of FFM, has been newly developed for the purpose of observation on nano machining in the scale from 1 to 100 nm. The system has both an original micro*cantilever for machining and an ordinary micro cantilever for AFM measurement, and it also has a device which can exchange two cantilevers alternatively. To evaluate the performance of the system, a single crystal silicon was machined and scratched by a single diamond grain which was fixed on the end of the cantilever. Then, the system could make 2μ m × 2 μm square holes of 70 nm in maximum depth. Moreover it also could make scratches obviously and measure the lateral reaction force at a time. Those results proved the system effective in nano-machining experiments.

Grinding Temperatures for Magnetic Ceramics and Steel

Grinding temperatures are measured using an infrared sensor in ferrite and steel. For reference purposes, temperatures are also measured in a reduced model for grinding which consists of a single diamond grain sliding across the workpiece surface at high speed. The results include temperature as a function of sliding velocity, rate of temperature decay as the grain moves away from contact, and histograms of the frequency that grains on the grinding wheel attain a given temperature. It is found that temperature measurements can be used to detect out-of-roundness in the wheel. Finally, a simplified two-dimensional model based on a heat flux moving with constant velocity gives reasonably good agreement with experiment.