Electroplated diamond tools refer to diamond tools that are firmly wrapped by matrix metal on the substrate (steel or other materials) by metal electrodeposition, they are widely used in mechanical electronics, glass, building materials, oil drilling, and other industries. Electroplated diamond tools play a vital role in various industries such as mechatronics, glass, building materials, oil drilling, etc. These tools are designed to provide high efficiency, long life, and precise grinding capabilities.
To achieve these desired properties, the tool’s plated metal must not only be of high hardness and wear resistance but also be evenly distributed throughout the substrate. This even distribution is critical to prevent flaking of the coating and shorten the overall life of the tool. Certain industries, such as magnetic materials and ceramic grinding, have specific requirements for the bond between the coated metal and the steel substrate. For example, in the magnetic materials industry, powder grinding is carried out at a controlled feed rate of about 0.3mm. Likewise, the ceramics industry employs high-feed dry grinding techniques that require a strong bond between the coated metal and the steel substrate. During the production of electroplated diamond tools, manufacturers often give priority to the type of coating metal, hardness, and wear resistance, but often ignore the critical aspects of ensuring a strong bond between the coating metal and the substrate. Therefore, it is not uncommon for tools to peel off during actual use. This paper analyzes the causes of this problem and briefly discusses the solutions.
The three types of spalled coatings in electroplated diamond tools are:
Detachment of the coating to the substrate surface: The diamond-containing metal coating and the diamond-free metal undercoat are simultaneously detached from the steel substrate.
Layer flaking to metal undercoat: The diamond-free metal undercoat remains adhered to the steel substrate, while the diamond-containing metal coating flakes off the metal undercoat.
Delamination and separation of the coating metal in the diamond-containing metal coating: the coating metal in the contact area of the workpiece is not worn normally, but falls off in flake or powder form, while the diamond particles are not completely detached. This type of spalling often goes unnoticed, leading to false perceptions of poor adhesion or wear resistance of the coated metal. Continuous large pores on the tool surface may indicate this type of flaking when diamond grains break off during normal tool use.
Understanding these types of spalling can help identify specific problems and take appropriate actions to improve the bond strength and durability of plated diamond tools.
Causes of plating peeling off:
The pre-plating treatment plays a vital role in the adhesion and quality of the coating on the steel substrate. The following are some effects of pre-plating treatment: Surface cleaning: mechanical polishing and degreasing to remove foreign matter, oil, and other pollutants on the surface of the substrate. This ensures that the plating adheres directly to the metal surface without any impurities. Failure to adequately clean the surface may result in poor adhesion and flaking of the coating. Oxide Film Removal: Etching is the process of removing an oxide film layer formed on a substrate due to exposure to air or other environmental factors. Prior to electroplating, this oxide layer must be removed to expose the underlying metal surface. If the oxide film is not effectively removed, it will inhibit the formation of a strong bond between the coating metal and the base metal, resulting in poor adhesion. Activation: Activation is performed to provide a chemically active and clean surface for the plating process. It promotes the adhesion of the coating by improving the bond between the substrate and the coating material. Activation processes such as pickling or electro-cleaning remove any remaining oxide layers and create specific surface conditions that enhance adhesion between the substrate and coating. Overall, a good preplating treatment ensures that the substrate surface is clean, free of contaminants, and properly activated. This promotes a strong bond between the coating and the substrate for a high-quality, durable finish. Conversely, poor preplating treatments can lead to adhesion problems, coating failures, and reduced product performance.
In addition to poor pre-plating treatment, the reasons for the peeling of the coating are as follows:
Insufficient Surface Preparation: In addition to pre-plating treatment, the substrate surface should be thoroughly cleaned and prepared to ensure proper adhesion of the plating. Any contamination or irregularities on the surface can hinder the bond between the coating and the substrate, causing flaking.
Insufficient Plating Thickness: Plating thickness should be appropriate for the intended use. If the plating is too thin, it may not adhere to the substrate with sufficient strength, causing peeling. The coating thickness should be controlled within the specified range to ensure good adhesion.
Poor plating material quality: The quality of the plating material used will affect the adhesion of the plating. If the plating material is of poor quality or does not have the necessary properties, it may not bond adequately to the substrate, resulting in flaking.
Insufficient adhesion promoter: Adhesion promoters or bonding agents are often used between the substrate and the coating to enhance adhesion. Failure to use or incorrect use of adhesion promoters can result in poor adhesion and subsequent peeling of the plating.
Improper electroplating process parameters: It is necessary to optimize the electroplating process parameters, such as current density, temperature, plating time, etc., to obtain good adhesion. If these parameters are not set correctly, poor adhesion and peeling of the plating may result.
Post time: Jul-27-2023