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India develops tech for internal combustion engines

The International Advanced Centre for Powder Metallurgy & New Materials (ARCI) has developed an ultrafast laser surface texturing technology, which can improve the fuel efficiency of internal combustion engines.

ACRI is an autonomous research and development centre under the Department of Science and Technology (DST).

Laser surface micro-texturing, which offers precise control of the size, shape, and density of micro-surface texture features, has gained momentum as a way to control friction and wear.

According to a press statement released by the DST, in this technology, a pulsating laser beam creates micro-dimples or grooves on the surface of materials in a controlled manner.

Textures like these can trap wear debris when operating under dry sliding conditions and sometimes provide effects like enhancing oil supplies (lubricant reservoir), which can lower friction coefficients and may enable reduced wear rate.

Image credit: Department of Science and Technology

The texture surfaces were created on automotive internal combustion engine components, piston rings, and cylinder liners using a 100-fs pulse duration laser. The micro dimples of 10-20 μm in diameter and about 5-10 μm deep, which have been created with laser beams, had a regular pattern.

The created textures were tested in an engine test rig under different speeds and temperatures of coolant and lubrication oil, and it was observed that there was a 16% reduction in the lube oil consumption with the use of texture on the piston rings. The 10-hour lube oil consumption test shows that the blowby substantially reduced with textured rings.

The fabrication of a pattern of micro dimples or grooves on the surface of materials results in a change in surface topography, which generates additional hydrodynamic pressure, thereby increasing the load-carrying capacity of the surfaces.

In order to control the friction, it is important to understand the mechanisms that occur during the conformal or non-conformal contact in dry and lubricated conditions. Ultrafast lasers create micro or nano features without vacuum conditions.

These features are smaller than the diffraction-limited laser focal spot diameter – a unique property of ultrashort duration laser-matter interaction. The process is a thermal, and pulse durations are orders of magnitude smaller than thermal diffusion times.

ARCI also recently developed a process for the size-selective deposition of nanocomposite coatings, which can reduce effects of friction on many aerospace, defence, automobile and space devices.

As OpenGov reported earlier, the scientists have found that nickel tungsten-based coatings with impregnation of particular sized silicon carbide (SiC) submicron particles can provide an excellent combination of wear and corrosion resistance with the low friction coefficient and a good oil retention capacity.

The coatings developed by the ARCI group could withstand corrosion from a salt spray better than many similar wear-resistant coatings available in the market.

The coating could address the emerging need for coatings with low friction and wear. Nanocomposite coatings with hard particles inside a tough matrix result in the best combination of wear resistance and reduced friction.

However, the size of reinforcement particles is a critical factor in deciding the friction characteristics. Too much variation in the size of reinforcement particles in composite coating results in premature failure of the coating due to stress concentration.

Electrodeposition, also known as electroplating, involves the metal parts to be immersed in an electrolyte bath solution, in this case, typically prepared by dissolving crystals of nickel and tungsten salts in a mix of distilled water and other additives.

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