The surface preparation of the brush plating on the diesel engine is as follows:
The preparation of the brush plating on the surface of the plating part of the diesel engine is a necessary condition for the smooth and successful process of the brush plating, including the surface of the brush plating and the removal of oil and rust, the protection from the surface, the electroplating of the brush plating surface and the activation treatment.
1 the grease and filth on the surface of the plating brush plating can be cleaned according to the degree of adhesion and organic solvent (such as industrial gasoline). If the cleaning work is large, the water agent metal cleaning agent should be used. The available steel brush on the surface can be removed by grinding or grinding with sand paper, and can also be removed by chemical methods such as hydrochloric acid.
2 if the brush plating is to repair the shaft or hole that has been worn, it is best to grind, remove eccentricity and remove the fatigue layer on the surface. For the hardened, carburized or nitriding yuan surface, as long as the fatigue layer does not appear, it can be retained without grinding. If the brush plating is to repair the defects on the surface, such as scratches, grooves and pits, it should be carried out first. Shape processing. First use flake wheel slotting, use hand tools such as scraper, oil stone and other hand tools to trim, remove burr, make groove mark and matrix face smooth transition. The narrow and deep groove should be properly widened, the width of the dressing is about 2 times of depth, so that the plating pen can contact the bottom of the ditch to ensure the quality of the brush plating.
For the pit formed after surface pressure injury or corrosion, it can be used to remove the rough objects, widen the root and mouth, and use oil stone and sand paper to repair the grinding. The width and depth of the dressing should be slightly larger than the original width and depth. If the surface scratches are very dense or the small pit is corroded, the tools, such as grinding wheels, scrapers, sanding and sandpaper can be used. Remove all the defects and make them smooth.
In general, the surface roughness of the machined surface should not be higher than Ral.6, and the roughness of the surface can be reduced to less than Ra0.8 by means of polishing and polishing.
3 the keyway and oil on the brush plating part of the 3 plating parts shall be blocked with graphite or wood and plastic plug, and the plug is trimmed to be as flat and smooth as the brush plating surface. The adjacent surface of the brush plating area adjacent to the non plating surface should be protected with plastic cloth, adhesive tape or insulating paint. Adhesive tape is used to protect the non plating surface. The 5 millimeter wide surface should be set around the brush plating to prevent the edge effect of the adhesive tape and make the deposition layer too fast.
After the treatment, the surface of the brush plating is often covered with thin film, and the surface of the metal under the oil film has an oxide film, which will reduce the bonding strength of the coating with the matrix metal. The electropurification and activation treatment is the final surface treatment procedure arranged to remove the oil film and the oxide film on the surface.
4 the electric net treatment on the surface of the brush plating. The plating pen dips the net liquid, brushes the surface of the brush plating on the surface of the brush repeatedly, the bubbles formed on the surface after the electricity is electrified, and the oil film is mechanically tore into the fine oil particles. The oil particles are emulsified and saponified by the emulsifier and the saponification agent in the net liquid, and are taken away by the plating pen and bath, because the hydrogen bubbles produced on the negative plate are more than the anode, The role of tearing the oil film is strengthened, so the plating parts are generally connected to the negative electrode, but for some steel parts that are easily permeable, they should be connected to the power cathode. The working voltage and time of the electroplating should depend on the material and surface of the plating.
The direct indication of the electric net is that there is a continuous layer of water film on the surface of the plating piece, and the water film will not gather into water droplets and spread out evenly. All the net parts of the electroplating should be rinsed with clean water to remove the residual liquid and other dirt.
The activation treatment on the surface of the 5 surface is followed by the activation treatment. The essence is to remove the oxide film on the surface by the acid solution, by chemical and electrochemical corrosion, and to etch the surface of the metal to expose the pure metal on the brush plating.
When activated, the plating must be attached to the positive pole of the power supply, and the plating pen is dipped in the activated liquid on the surface of the brush plating. The activation solution, the working voltage and the processing time should be selected according to the material and surface shape. For the steel with high carbon content, it is better to reactivate it, first use the No. 2 activation solution, and then activate the 3 activation solution to make the surface upstream. Removal of residual graphite and carbon black. Medium and high carbon steel and iron castings must be activated for two times.
The quality of activation can be judged by the color and uniformity of the visual surface. After the treatment of low carbon steel, the surface should be uniform silver grey and no spot. Medium carbon steel or high carbon steel is activated to black with No. 1 or No. 2, then activated to silver grey with No. 3 activation solution, and thoroughly rinse the surface with clear water after activation.
