Wyniki 1-3 spośród 3 dla zapytania: authorDesc:"Michał Kawiak"

Mikrostruktura i właściwości mechaniczne złączy lutowanych spieków ceramiczno-metalicznych i stali na dużych powierzchniach

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Możliwość wykorzystania zalet spieków ceramiczno-metalicznych, takich jak: wysoka twardość, odporność na zużycie ścierne, odporność chemiczna i termiczna, ograniczona jest ich małą ciągliwością. Dlatego w konstrukcji części maszyn i narzędzi z tych tworzyw należy dążyć do eliminacji lub zmniejszenia naprężeń rozciągających. Wymaga to właściwego podparcia elementu o małej ciągliwości, najczęściej w wyniku połączenia go z elementem wykonanym ze stali, cechującym się akceptowalną wytrzymałością na ścinanie, granicą plastyczności, udarnością, odkształceniem względnym i odpornością korozyjną. Złącze musi również spełniać szereg warunków geometrycznych, zapewniających szczelność konstrukcji i możliwość efektywnej kompensacji naprężeń wywołanych różnymi współczynnikami rozszerzalności[...]

Dobór materiału na fundamentowe podkładki maszyn DOI:10.15199/28.2015.6.37


  Material selection for foundation chocks of machines Large-scale machines and appliances are not placed directly on a foundation plate, but on foundation chocks. The chocks fulfil the role of compensation links that enable to place the founded object in a required position. For decades, foundation chocks have been made of steel and they never met with any substantial objections in terms of their function. With the passage of time, however, economic criteria has shown that foundation screw connections with metal compensation chocks were no longer the optimum solution. The question was whether it would be possible to improve the foregoing solution for foundation screw connection. Due to material engineering, a new innovative method was introduced, in which metal chocks machined outside of assembly place were replaced with chocks of polymer composite, cast directly between the foundation plate and machine base. In this case — as it is shown in the article — steel chocks were replaced with polymer ones that had worse mechanical properties. As a result of such an exchange, only seemingly did the construction deteriorate. The new construction form of foundation screw connections with cast chocks proved more advantageous than the foregoing solution in other important aspects and it is standard nowadays. Above all, the time of object foundation become ten times shorter. The presented issue of material selection for foundation compensation chocks shows that the best solutions are obtained when both mechanical and technological properties of material are taken into consideration in the course of its selection. Key words: machine, marine engine, foundation chock, polymer composite, mechanical properties, technological properties. Wielkogabarytowe maszyny i urządzenia nie są ustawiane bezpośrednio na płycie fundamentu, lecz na podkładkach fundamentowych. Podkładki te spełniają rolę ogniw kompensacyjnych umożliwiających nadanie posadowianemu o[...]

The structure of aluminide coatings on alloy steels in the area of the welded joints DOI:10.15199/28.2017.3.4


  1. INTRODUCTION Preparation of aluminide coatings is used to increase the heat resistance of Fe and Ni based alloys. The iron and nickel aluminides improve the resistance to many aggressive environments [1÷4] including oxidising [5÷10], sulphidising [11] and carburising [12, 13] agents. The method of the coating formation should be easy to apply on complex shaped parts and the cost should be as low as possible. One of these methods is the slurry cementation. Commercially available slurries manufactured on the base of aluminium powder (as an active component) and of the solution of an organic binder are widely used [14]. The slurry method used by the authors is a modification of the classical one. The slurry used in this modified method consists of a metal powder (aluminium and silicon), a binding material (the aqueous solution of sodium silicate) and halides as a flux. The aqueous solution of sodium silicate (inorganic binder) in the slurry allowed for annealing in one single step without additional heating when the organic binder is used. The main parameters determining the aluminide coating properties and usefulness are its chemical and phase composition and the thickness. The chemical composition of the aluminide coatings is characterized mainly by the aluminum content of these coatings. The thickness assessment and the analysis of the aluminum content of the coating are of primary importance for testing coating quality and protective properties [15]. The majority of final products working under a high temperature regime like equipment of furnaces for thermochemical treatment is made of high-alloyed steels and welding is the basic technology of joining of these materials. From a technological point of view, the first operation should be welding followed by manufacturing of a protective coating. Therefore, the characterization of the coating in the area of the welded joint can be important when choosing the proper welding [...]

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