Reasons for the Coating Falling off of Electroplated Diamond Tools:
Electroplated diamond tools involve multiple processes in the manufacturing process, Inadequate implementation of any process can cause the coating to fall off.
Effect of pre-treatment before plating:
The treatment process of the steel substrate before entering the electroplating tank is called pre-plating treatment, Pre-plating treatment includes: mechanical polishing, unoil, Steps such as etching and activation. The purpose of pr- plating treatment is to remove burrs from the substrate surface, greasy dirt, film, Rust and scale, To expose the base metal so that the metal lattice can grow normally, Forming inter-molecular binding forces.
If the pre-plating treatment is not good, There are very thin oil and oxide films on the surface of the substrate, The metal lattice of the base metal cannot be fully exposed, Will prevent the formation of inter-molecular bonding between the plating metal and the base metal, Just mechanical inlay, Poor adhesion, therefore, Poor pre plating treatment is the main reason for coating detachment.
Effect of plating solution:
The formulation of the plating solution directly affects the type, hardness, and wear resistance of the plating metal, Combining different process parameters can also control the thickness, density, and internal stress of the deposited metal crystals.
For the production of diamond electroplating tools, Most use nickel or nickel cobalt alloys, If the influence of impurities in the plating solution is not considered, Factors that affect the detachment of the plating layer include:
(1) Effect of internal stress The internal stress in the plating layer is generated during the electrode-position process, Additives in solution, their decomposition products, and hydroxides can increase internal stress.
Macroscopic stress can cause bubbles, cracks, and peeling off of the coating during storage and use.
For electroplating nickel or nickel cobalt alloys, Different bath compositions, Significant difference in internal stress, The higher the chloride content, The greater the internal stress, For plating solutions with nickel sulfate as the main salt, The internal stress of Watt type plating solution is smaller than that of other types of plating solutions, By adding organic brighteners or stress relievers, Can significantly reduce the macro internal stress of the coating and increase its micro internal stress.
(2) The effect of hydrogen evolution in any plating solution, Due to the dissociation of water molecules ,Regardless of its pH value, There is always a certain amount of hydrogen ion. Therefore, When conditions are appropriate, Electroplating is performed in either acidic, neutral, or alkaline electrolytes, At the same time as metal precipitation on the cathode, Hydrogen often precipitates, After cathodic reduction of hydrogen ions, Some form hydrogen gas and escape, while some infiltrate into the base metal and plating layer in the state of atomic hydrogen, Distortion of the lattice, causing significant internal stress, and significant deformation of the plating layer.
Effect of electroplating process:
If the composition of the electroplating solution and other process control effects are excluded, Power failure during electroplating is an important cause of plating detachment.
The electroplating production process of electroplated diamond tools is significantly different from other types of electroplating, The electroplating process of electroplated diamond tools includes empty plating (backing), sanding, and thickening processes, In each process, there is a possibility that the substrate will leave the plating solution, i.e., there may be a long or short power outage, Therefore, adopting more reasonable processes and procedures can also reduce the occurrence of coating peeling.
Contact Person: Mr. Lenny Li