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Determination of heat treatment parameters for heavily - loaded aircraft engine components

Rokicki P., Dychtoń K., Nowotnik A., Drajewicz M., Sieniawski J., Kurkowski D., Wierzbińska M, Jakubowicz G., Budzik G.

Journal of KONES

2013

Vol. 20, No. 2

349--354

Gears, due to their complex shape, carried load and required accuracy are ones of most complex aircraft engine parts. Single tooth damage usually breaks the power transmission and causes failure of the entire gear system. Adequate sustainability and guarantees of transmission is therefore a condition for secure operation of whole device. Particularly high requirements for reliability are put to transmissions used in the aerospace industry. Due to the loads which are transmitted through the gears, the materials used by the manufacturer must have not only high strength but also show the abrasion resistance of the surface layer and the ductility of the core. Proper parameters matching allows to create an element that can operate at higher stresses and loads. In addition, factor strength and abrasion resistance of the surface layer has a significant impact on the life of the gear. Thermo-chemical treatment of industrial gears is a fundamental process, which gives them adequate mechanical properties regarding loads they carry and the surface conditions of work. Among many methods of thermo-chemical treatment used in the industry, the most distinctive are innovative technologies designed to reduce process costs and being more environmentally friendly. The most promising methods in the discussed field are vacuum carburizing and high-pressure hardening, which by their specification of work significantly reduce the emission of CO2 and the duration of the process, without reducing the quality of the final product. The main aim of the paper is to present criteria for selection of heat treatment parameters as a part of thermo-chemical treatment process performed using vacuum methods. Proper heat treatment parameters are crucial in programming of some of final material characteristics as grain size and retained austenite morphology.

Porowatość i wytrzymałość form ceramicznych wykorzystywanych w procesie odlewania precyzyjnego metodą Bridgmana

Matysiak H., Ferenc J., Michalski J., Lipiński Z., Jakubowicz G., Kurzydłowski K. J.

Inżynieria Materiałowa

2011

Vol. 32, nr 1

17-21

Praca dotyczy badań właściwości wytrzymałościowych i porowatości dwóch rodzajów form ceramicznych stosowanych w procesie odlewania precyzyjnego łopatek turbin silników odlewniczych metodą Bridgmana (opartych na tlenku glinu i mulicie). Wyznaczono objętość względną porów, %, rozkład wielkości porów i średnią średnicę porów, ?m, gęstość materiału formy, g/cm3, wytrzymałość na zginanie, MPa, oraz moduł Younga, MPa, i moduł Weibulla. Badaniom poddano formy ceramiczne w trzech stanach: po usunięciu wosku (w stanie "surowym", T = 25°C) oraz po obróbce cieplnej w temperaturze 700°C i 1500°C.

The study of porosity and strength of two types of ceramic shells: (a) based on alumina and (b) on mullit was carried out. Weibull distribution was used to describe the statistical strength of the ceramic shells for Bridgman investment casting process. The porosity and average pore diameter were measured. Shells were tested: at green state, after burn-out at 700°C and after firing at 1500°C. It has been found that data obtained from the porosity examinations are in good agreement with strength results (average bending strength and Young modulus).