68results about How to "Avoid graphitization" patented technology

The invention discloses a PCD grinding wheel capable of performing positive rake angle processing and provided with an ordered micro slot structure and a manufacturing method for the PCD grinding wheel. The PCD grinding wheel is characterized in that a layer of polycrystalline diamond film, namely PCD film is deposited at the outer peripheral surface of a hub of the grinding wheel, wherein a plurality of micro grinding units with positive rake angles and micro slots with high depth-width ratios, which are orderly arranged, are processed in the outer peripheral surface of the whole PCD film. The manufacturing method comprises the following steps of: depositing one layer of PCD film on the outer peripheral surface of the hub of the grinding wheel through hot wire chemical vapor deposition, namely an HFCVD technology; processing a plurality of micro slots with high depth-width ratios, which have axial length equal to the thickness of the grinding wheel, peripheral width being only dozensof microns and depth being hundreds of microns, in the outer peripheral surface of the whole PCD film through a micro water-jet guided laser processing technology, and forming a plurality of micro grinding units with positive rake angles in the outer peripheral surface of the whole PCD film, wherein the micro grinding units and the micro slots are orderly arranged. The grinding wheel disclosed bythe invention can realize positive rake angle processing, remarkably reduces a grinding force ratio, improves grinding performance, further can increase holding force, on the micro grinding units, ofthe grinding wheel, and effectively prolongs the service life of the grinding wheel.

The invention relates to carbon paper and a preparation method thereof and particularly relates to special high-performance carbon paper for a gas diffusion layer of a fuel cell and a preparation method of the carbon paper. By taking short carbon fibers, plant fibers, heat bonding fibers and carbon black as raw materials, the carbon paper is prepared by the following steps: defibering, pulping and proportioning; then carrying out papermaking by adopting a wet-method papermaking process; and carrying out waterproof pigment coating treatment. The ratios of all the raw materials are as follows in parts by weight: 65-75 parts of the short carbon fibers, 10-15 parts of the plant fibers, 10-15 parts of the heat bonding fibers and 0-10 parts of the carbon black. According to the special high-performance carbon paper for the gas diffusion layer of the fuel cell and the preparation method of the carbon paper, a production process combining wet-method formation, hot pressing and coating is adopted and has the characteristics of simple process flow, easiness for controlling product quality, environment-friendly production process and the like; the material ratio of each raw material can be accurately controlled in the production so as to be good for controlling the product quality.

The invention discloses a method for improving the quality of diamond seed crystals by using hydrogen plasma multiple etching / annealing cycle technology, which relates to a method for improving the quality of diamond seed crystals. The present invention aims to solve the problems that the existing method for improving the quality of the diamond seed crystal takes a long time, the operation is relatively complicated, and the surface quality of the seed crystal is easily deteriorated. The method is as follows: 1. Diamond seed crystal cleaning; 2. Welding; 3. 1. Placing the seed crystal; 4. Hydrogen plasma etching / annealing, which is completed. The hydrogen plasma etching / annealing treatment of the present invention can simultaneously remove crystal defects, surface and subsurface damage, internal stress and defects of the diamond seed crystal caused by mechanical polishing on the surface of the diamond seed crystal in the same instrument, and improve the crystallinity, thereby obtaining High quality seeds and greatly simplifies operation, saving time and cost. The invention is applied in the technical field of crystal growth.

The invention discloses a diamond grinding wheel, which has multi-layer abrasive particle orderly arrangement, is high in bonding strength and is convenient to repair after being worn, and a production method thereof. The production method comprises steps of processing a grinding wheel basal body, cleaning and the like. According to the diamond grinding wheel and the production method thereof disclosed by the invention, a laser material increasing technology is adopted to accurately process, so that processing precision and processing quality are improved; a sandwich structure is adopted for sintering, so that the abrasive particles are prevented from moving, protruding height of the abrasive particles is guaranteed to be consistent, orderly arrangement of the diamond abrasive particles is realized, a chip space during grinding is great, grinding force is reduced, a grinding temperature is reduced, grinding efficiency is improved, and grinding surface quality is improved; power of a laser unit is controlled for controlling a sintering temperature, so that the diamond abrasive particles are prevented from graphitizing, and a metal bonder is combined with the diamond abrasive particles in a high-strength metallurgical mode; a manufacturing process further can be simplified; and the diamond grinding wheel is finished layer by layer after being worn, and then is continuously used, so that finishing is convenient, and the service life of the diamond grinding wheel is long.

The invention discloses a method for preparing a copper-based diamond composite material. The method comprises the following steps: processing a copper alloy / pure copper material into a final size of a diamond / copper product to serve as a mold, then pouring diamond single crystal / coated diamond granules into the mold, jolt ramming, and dripping an adhesive solution; vacuum treating at 200-600 DEG C to prepare a porous diamond skeleton blank; filling the porous diamond skeleton blank and the copper alloy / pure copper mold in a sheath, carrying out hot isostatic pressure treatment, and cooling to obtain the composite material. The method disclosed by the invention can be used for achieving near-net forming, the post processing capacity is small, the process is simple and reliable, the prepared diamond / copper composite material is good in performance uniformity, the material has good comprehensive performance with being used as an electronic package material and a radiating substrate material, the thermal conductivity of the material can reach 700w / mk, the thermal expansion coefficient can be freely adjusted and is not less than 6.5*10<-6> m / l at a room temperature condition, and the density is higher than 99.9%.