Sustainable Solution to Low-Cost Alternative Abrasive From Electric Ceramic Insulator Waste For Use in Abrasive Water Jet Machining

Increasing demand and resource overuse has prompted the exploration of spent secondary materials as a primary raw material for a variety of applications, leading to a more sustainable environment. Spent electric grid ceramic insulator, one of the waste materials of ceramic industry has a good hardness and strength. It can be reused as value added material in Abrasive Water Jet Machining (AWJM) industry. This present work deals with conversion of electric insulator rejects (EIR) into a cost-effective replacement material for abrasive water jet machining process. Mechanical crushing method is opted to generate the abrasive grit for the machining process. Grit generation pattern and the friability of the electric insulator rejects were determined experimentally. The results indicate that the friability of the processed electric insulator rejects is comparable with the commercially available garnet abrasive. Geometric parameters such as sphericity, elongation ratio, and shape factor for the processed electric insulator rejects were studied using scanning electron microscopy. The machining performance indicators for standard aluminium material such as volume of material removal, kerf angle, surface roughness and cutting width were measured for electric insulator rejects and compared with existing garnet abrasive grain. The experimental results of newly generated electric insulator reject abrasive were matched with performance indicators of the garnet abrasive. The observed deviation was lower proving that it can be used as alternative abrasive in the abrasive jet machining process. Cost analysis and recycling ability predict the economical usability of the newly generated abrasives.

Heating and Cooling Impact on Mechanical Properties of RIP Electric Insulator for High Voltage Inputs

The mechanical properties investigation results obtained by tension and indentation tests of RIP (resin impregnated paper) electric insulator are presented. Tension and indentation tests of the RIP electric insulation material in wide temperature range are conducted. The common relations between strength and temperature as well as between hardness and temperature for the RIP electric insulation are established. The ratio of ultimate tensile strength to Brinell hardness is performed to be constant (about 1/3) irrespective of temperature, that means a possibility of the RIP electric insulation mechanical properties evaluation by the instrumented indentation test.

Development of Coating Process Technique for Anti-Fouling Electric Insulator

In order to improve the anti-fouling characteristics of the electric insulator for electric railway, a functional coating for preventing pollution was carried out on the surface of the T type post insulator and long rod insulator in the railway insulators. In order to ensure the durability of the thin film on the coated insulator surface, the coating was annealed at three different annealing cases by using a furnace. Case 1 is annealing treatment at 250°C and case 2 is annealing treatment at 400°C. Case 3 is the double annealing treatment (case 1 + case 2). The film Surface conductivity and anti-fouling characteristics of the insulators annealed at three temperature conditions were measured. It was confirmed that the insulator annealed in case 3 had both good conductivity and anti-fouling characteristics.

Use of Electric Discharge Sintering for Elaboration of Diamond Tools

A number of installations for electric discharge sintering of powder materials is developed. There are installations in which energy is delivered by following currents: 1) superposition of the direct and alternating (with frequency up 7900 Hz) currents, 2) alternating current (50 Hz). The sintering is carried out in conductive (graphite) moulds. The sintering is often done in thermal and electric insulator moulds (for example, ceramic on Si3N4 base, asbestos cement). At sintering of metal-diamond composition in insulator moulds metallic electrodespunches (steel) are used. Such a variant of sintering allows one its duration to short from ~900 s down to ~60–150 s. This ensures complete safety of dimensions and operating characteristics of diamond grains. The technologies of various diamond elements for tools for treatment of glasses and soft stones (stone saws, tools in forms of tablets, rings). The preliminary pressure which is applied to powder sample simultaneously with current was equal to ~10 MPa (~100 kg/cm2). The end pressure was equal to ~100 MPa (~1000 kg/cm2). The current density was equal to ~700– 1200 A/cm2. Tests of diamond tablets (diamond 20/14 mkm, binder 80 % Cu+20 % Sn) at grinding of glass had shown: the abrasivity of tablets with common diamonds is equal to ~50 g/(cm2 min), and abrasivity in case with diamonds annealed in hydrogen is equal to ~70 g/(cm2 min).