The sintering temperature and holding time have a significant impact on the densification of a ceramic compact. In this study, alumina inserts were made with varying sintering temperatures and holding times. The procedure began with the compacting of alumina powders inside a mould with trapezium and round shapes. These inserts were then sintered between 1200 °C and 1400 °C for 5 to 9 h holding time. The sintered samples underwent analysis based on the shrinkage size, density, and microstructure. The sample with the highest density was chosen for additional machining tests. The results showed that the alumina shrinkage ranged from 3 to 6%, with a maximum relative density of 91.3% recorded when the sintering parameter was applied at 1400 °C and a 9 h holding time. The transition of the grain growth was observed depending on the sintering temperature and heating duration. When machined with AISI 1045 carbon steel, the sintered alumina inserts achieved a maximum tool life of 35 s at a cutting speed of 350 m/min. The sintered inserts exhibited brittle characteristics with a dominant notch wear and abrasive mechanisms.
This paper presents the development of resistance heating furnace based on the direct electrical conduction method that can perform with lower energy. Based on the concept of resistance welding, resistance heating furnace was developed for heat treatment of 22MnB5 Boron steel with the aim to change the microstructure from pearlite to austenite phases before quenched into martensite phase. The main component for this machine consisted of transformer, copper electrodes, copper cable coil and wood frame structure. The design of the machine resembled resistance welding with upper and lower electrodes were assembled together mounted by the wood frame. The heating energy collected from the electrical current that flow through cooper cable that rolled through toroidal transformer. The result shows that the machine capable to heat the 22MnB5 Boron steelwith maximum temperature of 721.2°C. However, the machine demonstrates overheat after 7 minutes due to the insulation burn of cooper cable. Further improvement of cooling system and copper insulation need to be addressed to prolong the heating operation.
22MnB5 Boron Steel can be considered as emerged material for high strength and low weight application. This material potentially used in abrasive condition such as cutting tool or brake pad where high friction resistance applies. In this study, the wear characteristics of 22MnB5 was investigated under the frictional tests via micro pin-on-disk. 22MnB5 Boron Steel was prepared the form of round shape within the size of 2.6 mm thickness and 12 mm diameter by using laser cutting. 4 different samples were tested namely blank (sample A), self-hardening heat treatment (sample B), 60 HRC hot stamped (sample C) and 70 HRC hot stamped (sample D). The results show that Coefficient of Friction (COF) increased as the hardness of 22MnB5 decreased. Low COF of 0.2114 recorded for sample D with 70 HRC hardness. The COF increased to 0.24, 0.29 and 0.3 when sample C (60 HRC), sample B (52 HRC) and sample A (45.5 HRC) applied respectively. For pin-on disc test, worn area decreased as the hardness increased. 22MnB5 that prepared with the highest hardness of 70 HRC presented smallest wear area of 700 µm x 2400 µm. It is followed by 800 µm x 2400 µm, 1000 µm x 2400 µm, 1600 µm x 2800 µm, when sample C, B and A were scratched. Observation on the worn surface revealed delamination of 22MnB5 surface in the form of fragmented flaking debris.
22MnB5 Boron Steel can be considered as emerged material for high strength and low weight application. This material potentially used in abrasive condition such as cutting tool or brake pad where high friction resistance applies. In this study, the wear characteristics of 22MnB5 was investigated under the frictional tests via micro pin-on-disk. 22MnB5 Boron Steel was prepared the form of round shape within the size of 2.6 mm thickness and 12 mm diameter by using laser cutting. 4 different samples were tested namely blank (sample A), self-hardening heat treatment (sample B), 60 HRC hot stamped (sample C) and 70 HRC hot stamped (sample D). The results show that Coefficient of Friction (COF) increased as the hardness of 22MnB5 decreased. Low COF of 0.2114 recorded for sample D with 70 HRC hardness. The COF increased to 0.24, 0.29 and 0.3 when sample C (60 HRC), sample B (52 HRC) and sample A (45.5 HRC) applied respectively. For pin-on disc test, worn area decreased as the hardness increased. 22MnB5 that prepared with the highest hardness of 70 HRC presented smallest wear area of 700 µm x 2400 µm. It is followed by 800 µm x 2400 µm, 1000 µm x 2400 µm, 1600 µm x 2800 µm, when sample C, B and A were scratched. Observation on the worn surface revealed delamination of 22MnB5 surface in the form of fragmented flaking debris.
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