Services and applied activities
Different activity in the scope of services is realized in the Tribology Center at the Technical University of Sofia:
Industrial applications: Tribotechnology for regeneration of worn details by means of deposition of composite wear-resistant coatings; Ecological tribotechnology for regeneration of air automotive filters, etc.
Laboratory testing: Services by the use of procedures and devices for testing friction, wear, lubrication, hermeticity and reliability of coatings, materials and contact systems.
Two of the industrial applications are described below
Wear-resistant metal powder coatings
The coatings are obtained in a flame medium of acetylene and oxygen mixture. The powders are combinations of super-alloys of different content and properties.
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The obtained coatings have high adhesion with the base surface due to the chemical bonds; they have different hardness (up to 70 HRC) and resilience depending on the requirements of the client.
Compared to the widely used in the country technologies like welding, metalizing, cold overlaying, chrome plating, nitriding, above tribotechnology has the advantage to produce coatings with wear-resistance 3 to 8 times higher than that of the non-coated new detail.
The tribotechology allows not only regeneration of the dimensions of the worn elements, but also to improve the wear resistance of the surfaces of new elements.
The method is used in the Laboratory of Tribology at the Technical University Sofia for the regeneration of great scope of details, mainly in the field of the automotive transport: elements in the braking system, crankshafts and countershafts in the engines, compressor shafts, rods in tow-trucks, bearing grooves, bolts for steering knuckles, rotation elements, turbines, engine covers, pumps, etc.
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Some concrete applications
- regeneration of shafts of different pumps;
- engine rotors, bearing surfaces;
- engine covers, bearing grooves, surface cracks;
- different shafts bearing and other working surfaces;
- cages of pumps;
- different wheels;
- rotation elements and turbines;
- fans and reduction gears;
- dies and other moulds.
Tribotechnology for regeneration of air automotive filters
Air automotive filters are regenerated for 15 years in the Tribology Center of the Technical University-Sofia. After regeneration they show high quality and reliability at the same operation characteristics as the new filter, and with several times lower price.
Brief about the tribotechnology
After identification of the state of the filter, and depending on the model and the degree of pollution, a different system of technological affect is used. The regeneration of the filter is realized by destruction of the formed in the operation parasitic dust coat (contact layer) on the working surface of the filtering matrix.
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There are three stages of the technology:
The first step is identification of the state of the filter realized by measurement of the integral and local contact conductance using the method of pneumo-hydraulic extreme of Prof. Manolov.
The second step is the regime of regeneration including actions as per a given algorithm in a tray with special surfactants at a given temperature of the multiphase medium; then comes treatment of the working surface by system of bi-phase streams and ultrasound by turbulizing the medium.
The third step is drying by centrifugation and hot air blowing. Finally comes fine cleaning through stream-striking impulses.
The technology allows up to four times regeneration of the original filter and guaranties 85% resource compared to the new filter. It leads to economic ecological effect.
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The existing manners in the exploitation of automotive filters
Widely used practice is the replacement of the old filters with new ones, so the old filters are waste matter.
There is an experience in our country to replace only the filtering element for trucks, using the case of the old filter. The filtering paper is imported. There are no methods and devices for qualification of the characteristics of the filter with replaced filtering element.
The filers are mostly consumer expendable elements.
The solution of the ecological problems involves new way of thinking and new approaches. The returnable use and regeneration of materials and products lead on one hand to avoiding the whole cycle of production, i. e. saving materials, energy and pollution; and on the other hand reduction in the price of the product.