2026-05-09
2026-05-09
Pre-treatment of single crystal diamond
Heat and acid-wash the diamond single crystal particles using aqua regia (concentrated nitric acid + concentrated sulfuric acid) to remove surface contaminants such as metal impurities and oxides, thereby preventing the formation of thermal resistance at the interface due to impurities. After acid-washing, the diamond surface becomes highly polar, making it prone to adsorbing ions and impurities. Multistage ultrasonic cleaning (alkali ultrasonic, deionized water ultrasonic, anhydrous ethanol ultrasonic) is employed to ensure the cleanliness of the diamond single crystal surface.
Basic Principles：
The powder processing technology, which utilizes high pressure to apply uniform pressure in all directions to the powder sealed in a flexible mold at room temperature, has a core advantage of high and uniform density of the green body.
key steps：
1. Loading and sealing: The powder is loaded into a flexible mold and vacuum sealed to prevent infiltration and contamination.
2、Pressurization and pressure maintaining: Place the sealed mold into a pressure vessel, fill it with pressure, and maintain the pressure to fully densify the powder.
3、Pressure relief and demolding: Slowly release the pressure, remove the mold, and peel off to obtain the greenware.
core advantage：
1 Extremely high and uniform density: The density variation can be controlled to be ≤1.5%, which is significantly better than that of unidirectional pressing (5%–10%), greatly reducing the risk of sintering cracking.
2 High green strength: easy to handle, store, and machine (turn, grind, drill).
3 No mold wall friction: no lubricant required, high purity, stable performance.
4 Wide range of applications: Capable of molding large-sized and complex-structured components.
Basic Principles：
The infiltration process belongs to the liquid-phase method. Molten metal (such as copper or aluminum) is infiltrated into the pores of the green compact under pressure or capillary action, and after cooling, a dense diamond composite material blank is formed.
Key steps：
1、Green compact preparation: Obtain fully densified green compacts through cold isostatic pressing.
2、Infiltration: Place the green compact in a vacuum chamber, with metal powder placed above it. Heat it to a temperature above the melting point of the metal under vacuum or a protective atmosphere, and apply a certain pressure (atmospheric pressure or mechanical pressure) to force the molten metal to infiltrate the green compact.
3、Cooling process: After cooling, remove the mold and proceed with subsequent finishing processes.
core advantage：
Ø High density (>98%), high thermal conductivity (up to 550–900 W/(m·K))
Ø The diamond has a high volume fraction, uniform distribution, and a low thermal expansion coefficient (6–8ppm K⁻¹)
Ø It can achieve rapid and high-quality molding, making it suitable for large-sized and complex structural components.
Basic Principles：
The vacuum hot-press sintering process is an advanced rapid sintering technology. The green body is loaded into a vacuum chamber and subjected to gentle pressure, causing the surfaces of diamond and metal particles to be rapidly activated, cleaned, and even melted. Simultaneously, pressure is applied axially to achieve ultra-rapid densification.
Key steps：
1、Place the green body into the vacuum hot pressing equipment；
2、Vacuumize or introduce protective gas；
3、pressurize；
4、Heating, heat preservation, cooling and demolding.
core advantage：
1、The sintering speed is extremely fast, with a temperature rise rate of up to several hundred degrees Celsius per minute, which can greatly inhibit grain growth and harmful interfacial reactions.
2、 It has extremely high density and can maintain a fine microstructure.
3、Suitable for the preparation of high-performance diamond composite materials.
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