Electroplating Improvement Research Diamond Tool (4)

2 Improve the contact area between diamond and carcass

2.1 Using surface roughened diamond particles

The roughening method is used to form some tiny pits and cracks on the diamond surface, and the surface of the diamond in contact with the carcass is increased to improve the mechanical integration force of the diamond and the metal, and enhance the "mechanical anchor chain" effect. A strong roughening method is: covering the diamond with a chlorine base salt (mainly NaCl + BaCl2) and a small amount of deoxidizing agent, covering with a ceramic crucible, heating in the furnace to 1000 ° C to 1100 ° C, and then holding the heat, and then The chlorine base salt is removed with boiling water. The diamond is heated, and the chlorine-based salt is melted to cause graphitization of the diamond corrosion, so that the surface forms minute rough pits and cracks. Another weakening method is to etch the diamond in a roughening solution (nitric acid + sulfuric acid or nitric acid + hydrogen peroxide) at room temperature or under heating, stirring constantly, and then washing it with distilled water. Diamonds form defects such as pits and cracks and slight graphitization under the corrosion of strong oxidizing acids.

2.2 Elimination of the tool between the diamond particles
because the carcass gap <br> <br> nonmetallic diamond belongs, no good affinity with the metal, resulting in a high interfacial energy between the diamond and the metal or alloy in general, often produce voids , reducing the bonding force between the diamond particles and the plating substrate. In this case, the particle surface modification method, the CVD method, the ultrasonic method, or the electroless plating method can be utilized to avoid or compensate for such voids.

2.2.1 Particle surface modification method [19]

The diamond particles are oxidized to form a hydrophilic chemical group on the surface, thereby improving the hydrophilicity of the diamond surface and tightly bonding the diamond particles to the plating layer. If the hydrophilic groups on the diamond surface are replaced by some more hydrophilic organic genes by chemical means, the effect can be further improved.

2.2.2 Electroless plating method [20]

Electroless plating is to deposit a metal on the surface of diamond by an oxidation-reduction reaction of an autocatalytic process without an applied current, thereby forming a uniform and dense film coating. It has been found that when a diamond tool is obtained by chemical composite plating, there is no gap between the diamond and the metal carcass. In addition, ultrasonic vibration will expand around the diamond particles, completely eliminating the gap. The particulate diamond can be directly electrolessly plated to obtain a tool which can be uniformly suspended in the plating solution. For large-grain diamonds, we recommend that you first perform electroplating and sanding to allow the diamond to be pre-embedded in the coating. The thickening process can be electroless.

3 to improve the chemical bonds between the particles and the binding
<br> <br> carcass by processing the diamond, so that the surface of the carbon atoms of the metal atom to form a metal / carbon chemical bonds, can solve the diamond and matrix binding diamond tool force is not Prison problem.

3.1 Surface metallization [21]

The surface treatment of the diamond particles by electroless plating can form a firm and tight connection between the diamond and the coating. However, if the diamond surface is completely metallized, the surface of the diamond particles has good electrical conductivity and is not suitable for electroplating to prepare diamond tools. In the process of burying sand, the plated diamond and the steel substrate and the plating layer together form a cathode, and a phenomenon in which a plurality of diamond particles are bonded to each other to form a block is formed. Therefore, the researchers used diamonds with dispersed conductive dots to make electroplated diamond tools [21]. The method is to control the degree of electroless plating on the diamond surface, strictly control the concentration of the sensitizing solution and the activating solution, and the time of sensitization and activation treatment, so that the number of metal dots on the diamond surface is kept within a suitable range. Although the number of conductive dots on the surface of the diamond increases, the connection point with the plated metal can be increased, and the bonding property between the plating layer and the diamond can be improved. However, when the metal dots are too dense, a thin layer of metal joined into a sheet is formed.

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