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DIARC Technology has announced its next-generation coating system that enables ta-C (tetrahedral amorphous carbon) structured diamond-like coatings to be produced in volume quantities.

This process is targeted at companies that need a hard-wearing protective coating that can deliver increased efficiency and reliability of components operating in challenging and critical wear environments in mechanical systems.

The latest generation of coatings from DIARC also offers extremely low friction in the presence of lubricants so support reduced energy consumption.

The super-lubricant coating has broad industrial applications for all types of wear parts in engines, hydraulic systems and power transmissions and also for precision tool applications.

‘In many cases the coated component or tool ensures a trouble-free operation of the machine and the production process,’ said Tapani Haikola, vice-president of DIARC.

‘On tools, for example, the improvement in service life offered by the coating plays a more important role.

‘Also, improved quality and more efficient production gained when using coated tools is in many cases as important as the service life of the tools,’ added Haikola.

DIARC has developed a low-temperature vacuum plasma deposition process that can lay down a thin, tough layer of diamond-like carbon onto a range of materials from metals to plastics.

The process is based on a special plasma accelerator technique to create highly ionised plasma of the coating material.

The plasma is electromagnetically accelerated to a high velocity (energy), directed towards the workpiece and targeted onto the surfaces to be coated.

This principle makes it possible to process well adherent dense coatings at low temperatures.

Typical deposition temperature is below 100C.

The temperature can be adjusted by the process parameters so that it is possible to make coatings at even lower temperatures (approximately less than room temperature).

The thickness of the coating can range from a few nanometres to several micrometres, depending on the application.

The coating process has low energy and raw material demands and no hazardous chemicals or gases are used in any phase of the process.

The ta-C structured hydrogen-free diamond coating developed by the company has five key properties of low friction, high hardness, excellent wear resistance, chemical inertness and high thermal conductivity.

The DIARC coating process also allows the properties of the coating to be graded so that the coating properties and performance can be optimised for a specific application.

‘The excellent wear resistance the coating protects the surfaces as a thin layer,’ said Haikola.

‘As a comparison one micrometre layer of amorphous diamond wears out in the same time as 1mm of hardened steel,’ added Haikola.

On modern machine constructions the wear is, in general, well in control and the main challenges are to prevent unexpected failures such as seizure of the moving parts.

This may happen in overloading conditions or when the lubrication does not work properly or lubrication is ceased for some reason.

The coating ensures reliable and trouble-free operation (preventing seizure) of pneumatic components such as valve actuators for process valves in chemical, oil and pulp and paper industry and on plungers of precision pumps of ventilators.

In a radial piston hydraulic motor, coating the sliding surfaces of the moving parts increased the efficiency at low speeds by 30 per cent compared to the efficiency with normal uncoated parts.

In power transmissions, the friction coefficient has been reported to be 25 to 30 per cent less when the gear wheels are coated with DIARC Diamond coating when compared to uncoated steel gear wheels.

DIARC’s system is designed for coating small parts in quantity.

The maximum dimensions of parts the company can coat are 660mm diameter, 700mm length (up to 1,000mm) and weight 250kg.

DIARC Technology

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