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Wednesday, May 23, 2001



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Coating surfaces with the D-Gun

M. Somasekhar

SAI Surface Coating Technologies is a small and medium enterprise (SME) parked in the technology entrepreneurship park promoted by the International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI).

The interesting aspect of the entrepreneur-driven venture is the application of detonation spray coating using the D-Gun, one of the most cost-effective solutions to problems of wear, corrosion, erosion and high temperature.

It is an interesting partnership effort between a first generation entrepreneur, Mr M. Nageshwar Rao, and associates, and the R&D institute ARCI, with funding by the Technology Information Forecasting and Assessment Council (TIFAC).

The technology of spray coating and the indigenous version of the D-Gun were developed by the ARCI. The total project cost is estimated to be around Rs 54 lakh. Of this, TIFAC has funded 50 per cent under its Home Grown Technologies (HGT) scheme. Sai Coa tings, promoted by three partners, has raised the balance through bank loans and has set up a functional job shop at the Park, in which the ARCI has provided the necessary infrastructural support.

Detonation spray coatings are considered one of the best thermal spray coatings suitable for any kind of surface. Using the D-Gun, advanced and hitech coatings, such as carbides, ceramics and composites, can be sprayed on almost any kind of material surf ace. The powders of these materials essentially help in improving the life of the components that are subjected to coatings in many ways.

Interestingly, the coating thickness achieved by Sai Coatings has been: for carbides (20 to 500 microns); for oxides (50 to 1,000 microns) and for metals and alloys it has been improved to thickness of upto a few mm.

Some of the important industries where the coating technology has been demonstrated are cables, aerospace, automotive, chemical, electronics, glass, marine, microwaves, Defence, nuclear, paper and pulp, plastic, printing, textiles and pumps.

The ARCI had originally sourced the D-Gun technology from the Institute of Problems in Material Science, Kiev. In the last few years, it not only indigenised but also developed an advanced detonation spray coating technology.

There are more than half a dozen technologies for coating surfaces. These include thermal spray, laser surface modification, plasma diffusion, diamond-like, cubic boron nitride and wear resistant coatings. Each of these also has its own unique applicatio ns.

The basic advantage of these technologies is they help material surfaces to ward off degradation, especially in adverse and hostile environments where they are subjected to corrosion, and fast wear and tear.In the D-Gun, the desired material to be used f or coating the surface, say a carbide, is accelerated to high velocities by detonation of explosive gas mixtures. It is then made to impinge on a substrate to form a protective layer of coating on the identified metallic surface. The process takes a few seconds and the coating remains for a long time.

The ARCI has decided to license the D-Gun technology to four small companies at different locations in the country, so that all of them would have adequate opportunities to grow, explained Dr G. Sundararajan, its Director.

Consequently, the technology has been transferred to three companies _ Sai Surface Coatings, Hyderabad; Shafel Tech, Chennai; and Associated Plasmatron, Mumbai, in the last six months, he said.

For Sai Coatings, the venture has begun well. It is averaging a revenue of Rs 4 lakh a month, on an average, since November, 2000. ``We have set a target of reaching Rs 1 crore during fiscal 2001-02,'' Mr Nageshwar Rao said.

One of the impressive jobs done by Sai Coatings was the imported substitution contract for Dresser-Rand India, Ahmedabad. The company was importing copper shafts at Rs 3.5 lakh each, used in the high pressure gas compressors of its fertiliser manufacturi ng units from the US.

After the detonation spray coating job done by Sai Coatings, Dresser-Rand successfully brought down the cost of each shaft o Rs 1.5 lakh. They are also meeting the performance standards and, in a reverse move, Dresser-Rand has decided to export the coppe r shafts to the US very soon.

Mr Nageshwar Rao thinks that plasma coating is the main competitor to the D-Gun technology now. Though a bit costly, D-Gun coating offers many advantages and, in some areas, is the only choice. With this confidence, he hopes to market aggressively and in crease his client base to at least 100 by the end of this fiscal.

The ARCI is also doing its bit in getting customers for Sai Coatings. At present, the company has job works with the Visakhapatnam Steel Plant and Andhra Machine Industries, and is in talks for strategic applications such as aerospace engines with both A ir-India and Hindustan Aeronautics Limited (HAL).

In another venture in the Park, the ARCI is itself an investor and promoter. ARCI and Hytech Blue Metal Powder Alloys joined hands and set up a carbothermic reduction facility to produce powder metallurgy (PM) grade sponge iron from blue dust, a waste ma terial from iron mines.

Under the Joint Venture (JV) Hytech has established a pilot plant of 180-200 tonnes per annum (tpa) at the Park. The high purity, low carbon PM grade sponge iron powder finds application in automobiles, railways, aircraft brake linings, clutch plate faci ng and soft magnetic products. Plans are on to set up a 3,000 tonne per annum (tpa) commercial plant.

According to estimates by the National Mineral Development Corporation (NMDC), about 22 million tonnes of blue dust is available in the form of haematite in various mines in the country. The Swedish giant Hogeanas holds a virtual monopoly in the world ma rket, producing and selling nearly 35,000 tonnes of the PM grade iron powder annually.

The JV has temporarily slowed down in getting into the commercial scale production, since the country's powder metal industry is witnessing sluggish growth. Sundram Fasteners, with a 2,000 tpa captive plant for iron powder production using atomisation of scrap; and Mahindra Sintered, with technology from Hogeanas, are the two lead players at present, though neither of these companies uses blue dust as raw material for iron powder production.

Pic.: Products spray-coated using the D-Gun developed by Sai Surface Coating Technologies. The gun can be used for detonation spray coating and is an effective solution to problems of wear, corrosion, erosion and high temperature.

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