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EN
Purpose: The purpose of this work is to explain the reasons for improved cutting properties of coated tools made of nitride and sialon ceramics by means of investigations into mechanical properties, including microhardness, adhesion and abrasive resistance of the coatings deposited and by means of investigations into the chemical composition and structure of the coatings. Design/methodology/approach: Investigations were performed in the framework of the work accomplished encompassing the following in the first phase: the development of a technology of deposition graded and multiphase coatings using the cathodic arc evaporation (CAE) methods; investigations were carried out in the second phase into the structure and properties of coatings deposited onto ceramic tool materials with the following required properties: high adhesion, microhardness, high resistance to abrasive, corrosive and diffusion wear in the working conditions of high-performance cuttings tools. Findings: The coating deposition technologies (coating systems) employed for coatings deposited in PVD processes of cathodic arc evaporation (CAE) and in a high-temperature CVD process on tool ceramics are eligible for widespread industrial applications. Practical implications: Investigations into the service life have allowed to select coatings with the best cutting properties: (Al,Ti)N, (Al,Cr)N, (Al,Cr)N+(Ti,Al)N and T(C,N)+TiN deposited onto sialon ceramics and (Ti,Zr)N, (Ti,Al)N, Al2O3+TiN (1), Al2O3+TiN (2), TiN+Al2O3+TiN, TiN+Al2O3, TiN+Al2O3+TiN+Al2O3+TiN deposited onto nitride ceramics exhibiting best cuttability, which is correlated with their high adhesion to the substrate and high hardness. The above-mentioned coatings enhance the lifespan of a cutting edge by up to 550% and for this reason, the coatings are eligible for widespread industrial applications in cutting tools. Originality/value: An original achievement of the work - as a result of the conducted cutting tests with varied technological parameters and based on the results of investigations of mechanical and structural properties - is that an application recommendation is proposed for the developed PVD and CVD coatings deposited onto ceramic tool materials for industrial applications.
PL
Obniżenie temperatury spiekania ceramiki azotkowej można osiągnąć przez zastosowanie procesu obróbki mechanochemicznej zestawu wyjściowych proszków, ale taki zabieg będzie prowadził do zmian mikrostruktury w stosunku do standardowych wyrobów i tym samym zmian właściwości. W ramach niniejszego artykułu przeprowadzono badania wpływu parametrów procesu spiekania (czas, temperatura i układ krzywej nagrzewania) proszku Si3N4 z dodatkiem AlN oraz Y2O3 po aktywacji mechanochemicznej na właściwości wyrobu finalnego. W ramach badań określano zmianę gęstości, porowatości, oraz twardości (HV) spieków. Przeprowadzono również szacowanie odporności na kruche pękanie (KIc). Badania dylatometryczne pozwoliły wyznaczyć najlepszą krzywą spiekania, natomiast obserwacje struktury metodą LM/SEM umożliwiły śledzenie zmian struktury wynikających z procesu spiekania.
EN
The temperature of nitride ceramics sintering may be lowered in the process of mechanochemical treatment of the initial set of powders, but such a procedure will cause microstructural changes in relation to standard products, and consequently will result in the change of properties. For the needs of this article, the authors conducted investigations into the infl uence of parameters of sintering (time, temperature and heating curve arrangement) of Si3N4 powder with an addition of AlN and Y2O4 after mechanochemical activation on the final product properties. Changes of density, porosity, absorbability and hardness (HV) of sinters have been determined. Fracture toughness (KIc) has also been estimated. Dilatometric tests allowed the best sintering curve to be determined, while LM/SEM structural observations enabled tracking the structural changes which result from the process of sintering.
PL
W pracy przedstawiono wyniki badań struktury i własności wielowarstwowych i gradientowych powłok PVD (Physical Vapour Deposition) i CVD (Chemical Vapour Deposition) wytworzonych na podłożu z narzędziowej ceramiki azotkowej Si3N4. Przedstawiono kompleksowe wyniki badań na transmisyjnym i skaningowym mikroskopie elektronowym, wyniki badań własności mechanicznych i skrawnych badanych płytek wieloostrzowych.
EN
Comprehensive structure and properties investigation results of the multilayer, gradient PVD and CVD coatings developed on the nitride tool ceramics substrate are presented in the paper. The detailed results are presented of examinations carried out on the scanning and transmission electron microscopes, as well as of the mechanical properties and cutting tests of the investigated inserts.
EN
The effects of the oxygen and titanium contents in the reactive layer deposited on nitride ceramics on the wettability and sintering capability of the metallic layers were examined. The deposited metallic layers were standard Mo and Mn layers with the oxygen content ranging from 0 to 40 at.% and the titanium content from 0 to 8 at.%. The layers were sintered at a temperature between 1573 and 1653 K in a hydrogen atmosphere (dew point - 203 K). In the a transition layers, between the Al2O3, or AIN ceramic material and the metallic layer, a continuous glass layer is formed on the ceramic surface, which wets very well both the substrate and the metallic powders.The microstructure of the metallic layers was examined using a scanning electron microscope and an electron probe. It has been found that both Al and Si migrate strongly to the interface layer. The microstructure of the metallic layers sintered on AIN differs from that of the layers sintered on alumina ceramics. In the interface layer formed between the ceramic material and the metallic layer, a continuous glass layer forms on the ceramic surface; the glass wets very well both the substrate and the metallic powders. The metallic layer is compact, and the solder does not flow in-between the grains. Based on the results of the microstructural examinations, the mechanisms of the sintering of Al and AIN ceramics are compared.
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