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PROCESS FOR PRODUCING
MULTICOMPONENT CARBIDE COATINGS
(Based on USSR patent # 1452190) - 72Kb (*.jpg)
Broad Area of Technology:  Materials Science and Engineering, Composite Materials 
Narrow Field Thermal and Thermochemical Treatment, Hardening of Tools
Purpose: The process permits increasing the performance, service characteristics and life of tools and machine parts made of steels, cast irons and hard alloys 

Brief Description and Specific Features

The process involves diffusion treatment of tools and machine parts (in a way similar to pack carburization) in metal oxide powder media during 4-6 h at the temperatures not exceeding 1000 °C (the chemical composition of the media and the temperature constitute the "know-how"). The treatment results in the formation of a uniform multicomponent carbide coating on the surface of the items. The thickness of the coatings is 4 - 7 mm on hard alloys, up to 70 mm on steels and up to 140 mm on cast iron; the microhardness is HV 2800 - 3700, which is close to that of silicon carbide. With the addition of a carburizing agent, the powder media permit obtaining coatings of a desired thickness on tool steels. The structure of the coatings is composed of globular alloyed carbides, the surface hardness being HRC 65 - 70.

Advantages Over Known Methods of Surface Hardening

bullet2the process is more simple and economical due to the use of standard equipment, cheap metal oxide media which allow multiple usage, and relatively low temperature

bullet2it does not require thorough cleaning of the surface

bullet2due to high thickness of the obtained coatings, the process allows for the subsequent sizing of the articles made from steels and cast irons

bullet2the technology is most efficient for disposable (not subjected to resharpening) hard alloy tools. For example, 1 kg of the powder medium (the cost is $20 - 30) used twice permits to process 1 - 2 kg of hard alloy tools (the cost is $100 - 300 per kg) increasing the wear resistance by the factor of 3 to 4, the strength of the material being unaffected. Moreover, sintering of the hard alloy may be combined with the diffusion treatment in the powder media.

Results of Testing in Industry

The use of multicomponent carbide coating produced by the developed process gives an opportunity to increase the service life of hard alloy cutting tools by the factor of 2 to 20 and the life of steel tools and machine parts by the factor of 2 to 5.

Examples: the increase of service life of processed tools, times:

  • disposable hard alloy tablets used for final turning 4 - 6;
  • disposable hard alloy tablets used for milling 2 - 4;
  • whole hard alloy end mills for machining hardened (HRC 62) steels 5 - 20;
  • guide for winding coil springs 2 - 5;
  • parts of the engine of a racing car 3 - 5;
  • The process is easy to implement, uses conventional hardware and does not require high-skilled personnel. It has been tested and is used by several enterprises in Belarus and Russia.
     
    Possible Ways of Cooperation
     
    (1) The process is available "as is". The powder media for the treatment can be produced by the author and shipped to the customer.
     
    (2) The process can be modified to develop novel low-cost composite materials and new tools made from such materials. The materials possessing high strength and wear resistance and having the microhardness of about HV 3700 will be based on high-impact-strength brands of hard alloys. They will be used to replace expensive hard alloys and refractory compounds like boron nitride and others in the production of "tablets" for cutting tools. This work requires additional investments for carrying out joint researches with a foreign partner.

    For more information please contact the author:

    Dr Alexander Shmatov
    Belarussia State Polytechnic Academy
    65 F.Skorina Ave., built. 7
    Minsk 220027
    Belarus
    Phone: (375) 17 2581066 (home), 2399260 (office)
    Fax: (275) 17 2329137
    E-mail:
    shmatov@infra.belpak.minsk.by


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