Determination of the Sintering Dwell Time of Gearing Iron Based Composition by Using 900 KHZ Induction System

Abstract

In this study, iron based powder metal (PM) compacts are sintered by two different sintering methods. One of the sintering methods is conventional sintering, 2kW atmosphere controlled oven is used in the sintering application. TM compacts are sintered at 1120°C for 30 minutes. In the study other used sintering method is induction which is a novel and fast. PM compacts are sintered at a temperature of 1120°C for 1 to 10 minutes using a 900 kHz ultra-high frequency induction system (UHFIS) with a power of 2.8kW. Hardness, density and microstructure images of PM compacts are examined and compared each other.When the obtained results are evaluated, 30 minutes conventional sintered PM compacts test results' are reached in 5 minutes using by UHFIS. Thus, iron-based PM compacts are sintered in 6 times less dwell time while using the induction system. Keywords: Iron, PM, Induction, UHFIS, Sintering INTRODUCTIONProduction of the materials by the powder metallurgy (PM) method consists of homogenous mixing of various metallic or ceramic powders at micro-scale, shaping by pressing and lastly sintering by heating. PM Production is known as a fast and practical method. Although powder metallurgy method is generally used in the production of metallic materials, it is possible to produce many non-metal parts by using PM method nowadays. It is a very useful and less problematic method because the PM parts are in desired sizes after sintering process. The iron PM parts takes the first place, within the metallic PM parts. They can be produce fast and inexpensive. Iron-based PM parts are mostly produced in industrial applications by using conventional sintering methods. In the conventional sintering process very long batch type furnaces are used. For the sintering of these furnaces, heating to the needed temperatures and fixing them at the sintering temperatures provides significant energy consumption and energy cost. Different sintering processes are being used in order to provide the same sintering process. Among these are SPS (Spark Plasma Sintering), microwave sintering, hot pressing and induction sintering. Induction sintering has a very different place among other comparative sintering processes. During induction sintering process, induction current is passed through to the magnetic materials. At this point, PM compacts temperature is reaches to sintering temperature in 10-15 seconds. Iron and iron-based PM compacts can be successfully sintered with medium [1, 2 and 3] or ultra-high frequency induction systems [4 and 5]. Induction system is generally using in forging [6], heat treatment [7], welding [8, 9, 10 and 11] and casting [12 and 13] operations.