One of the areas of application of cubic HPHT (high temperature, high pressure) presses is the synthesis of composite materials and polycrystals based on extra hard materials of artificial origin: cubic boron nitride and lab-grown diamond.

The use of composites and polycrystals has a slightly wider application in metalworking than diamond-based ones. This is due to the difference in the physicochemical properties of cubic boron nitride and diamond. According to the synthesis conditions, cubic boron nitride has a greater affinity and, as a result, greater chemical activity at high temperatures with materials such as:

The production of composites and polycrystals is carried out using HPHT equipment (single-axis presses, cubic presses, cutting sphere-BARS devices) in high-pressure solid-phase cells.

The process of obtaining these materials is carried out in the stability zone of cubic boron nitride and diamond, and requires temperatures at the level of synthesis of these materials by the HPHT method. The production of composite materials is carried out by the method of sintering with the formation of a matrix containing metal and derivatives of the interaction of carbides, borides and nitrides. The matrix imparts the necessary strength, and the grains of extra hard materials the necessary hardness, which makes composites made of extra hard materials similar in structure to metal-ceramic hard alloys based on tungsten carbide, but significantly superior to them in terms of hardness.

Polycrystals are obtained either by direct sintering of powders of extra hard materials, or by synthesis in the presence of activators for the transition of carbon and boron nitride into cubic (extra hard form). Polycrystals have greater hardness than composites, greater compressive strength, and greater thermal conductivity. However, they have lower bending strength and greater sensitivity to thermal and shock loads that arise during operation. In addition, polycrystals are obtained at synthesis parameters significantly higher than those required for the industrial synthesis of cubic boron nitride and diamond. Thus, composite materials based on extra hard materials can be obtained in sizes significantly larger than those of polycrystals and using HPHT equipment at the same pressure in the hydraulic press system.

The main application of multifaceted cutting inserts made of composite materials based on cubic boron nitride is processing such as fine turning of parts made of high-alloy steels after heat treatment with high hardness and high precision requirements, such as shafts for various power plants (power engineering, shipbuilding). An alternative to fine turning is the use of abrasive belts and wheels. Abrasive machining has a much lower productivity than turning; it requires selection and replacement of abrasive tools with different grain sizes during processing in order to ensure acceptable productivity and the required class of accuracy and surface finish. In conditions when we are talking about boring internal surfaces, the complexity of selecting an abrasive tool increases noticeably, and the potential prospects for the transition to fine boring of difficult-to-cut materials increases significantly.

In general, composite materials and polycrystals have great prospects in many areas of industry, primarily due to their outstanding properties, approaching the properties of diamond single crystals. Past limitations associated with the maximum possible size of these materials are being successfully resolved by the introduction of more powerful press units, such as the HPHT model 850 cubic press.