Maxim Puchnin

The Effect of PVD Tungsten-Based Coatings on Improvement of Hardness and Wear Resistance

This article deals with the analysis and evaluation of coatings applications made by Physical vapour deposition on ceramics substrates. Main focus is on the application of tungsten and tungsten nitride coatings for functionally graded materials (FGM). The article focuses on analysis and evaluation of tungsten and tungsten nitride coatings with ceramics substrates. Firstly suitable deposition parameters of W and WN coatings, prepared by magnetron sputtering, were tested. Test coatings on tool steel substrate exhibited high adhesion and good mechanical and technological properties. Both tungsten and tungsten nitride coatings on selected ceramics substrates exhibited good mechanical a technological properties. Properties such as hardness, reduced elastic modulus and wear are discussed for each coating/substrate combination. Both coatings seem to be good candidates for application in field of FGM. The results of the presented experiment shows that the adhesion and the final quality of the coating depends on the type of chemical bond in the coating and in the substrate, and on the ability of the coating to deform plastically.

Structural Changes of Hot Work Tool Steel due to Heat load

The paper deals with the influence of thermal load on functionality of the Toolox 33 hot work tool steel equivalent to the materials of W.Nr. 1.2311, 1.2312, 1.2738 and P20 in order to assess its suitability as a material for glass manufacture preform. Using light and electron microscopy it was shown that the steel was highly unfitting for this application where the steel comes into contact with the hot glass. Regarding the evaluation of the microstructure, it was shown that intense decarburization reflecting on the fracture behaviour of the surface layer during the thermal load has occurred. This fact was confirmed by a static tensile test and hardness measurements. Moreover, the thick layer of flakes has formed on the surface.

MICROSCOPIC EVALUATION OF THE QUALITY OF DENTAL REPLACEMENT

The permanent tooth replacements including metal-ceramic crowns are a convenient solution for the renewing of the original function of the whole set of teeth as well as of the natural appearance. Development and preparation of suitable tooth replacement presents a real challenge for dental engineers as the replacement has to meet all the conditions and requirements of the dental medicine as well as patient’s needs and wishes. The preparation of the metal-ceramic crown is a sophisticated process and the dental engineer has to prepare alwaysa unique replacement on demand. In dental medicine there is a wide spectrum of inorganic and organic materials used formanufacturing of dental replacements. Each of the material has specific properties leading to distinct applications.Besides the material properties, the attention has to be paid to the aesthetic function and biocompatibility of the material to ensure thecomplete restoration of the whole set of teeth.

MULTILAYER COATINGS Ti/TiN, Cr/CrN AND W/WN DEPOSITED BY MAGNETRON SPUTTERING FOR IMPROVEMENT OF ADHESION TO BASE MATERIALS

The paper deals with evaluation of single and multilayer layer PVD coatings based on Cr and Ti widely used in tool application. Additionally, W and WN based coating which are not so widespread were designed and deposited as functionally graded material. The coatings properties were evaluated from the point of view of hardness and adhesion. The hardness measuring was carried out using nanoindentation method. The scratch test was performed to test adhesion. Moreover, the presence of metallic interlayer in functionally graded materials further increases the coating adhesion by gradually approaching its composition to the substrate. Coatings consisting of W and WN have showed very good adhesion. With regard to the results of the scratch test, the multilayer coatings of CrN, TiN and WN have increased adhesion and can be assumed to have their protective function improved. Results will be appliedin development of functionally graded layers for functionally graded materials.

FEATURES OF STRUCTURE FORMATION AND CHANGES IN THE MECHANICAL PROPERTIES OF CAST Al-Mg-Si-Mn ALLOY WITH THE ADDITION OF (Ti+Zr)

The as-cast and heat-treated structure of permanent mould castings of AlMg 5 Si 2 Mn alloys with different contents of Ti has been investigated by differential scanning calorimetry, hardness and microhardness measurements, tensile tests and fractography analyses, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray analysis. We have established that α-Al dendrites can be nucleated on an Al-Ti substrate, and also that primary Mg 2 Si crystals can be nucleated on oxides, including oxides of Al and Ti compounds. The dependence of the change in mechanical properties on ageing time, and on the amount of Ti in the alloys, is shown.

The Effect of Microstructural Features on Mechanical Properties

Every material is structured in its unique way and has its own recognizable microstructure. There are a number of approaches in establishing the relationship between mechanical properties and microstructure of a material, but none of them is universal and correlation free, probably because of luck of attention to the sub-grain structure. The possibility of calculating the hardness number using only geometric sizes of microstructural formations is discussed in this paper, where the grain is meant to be a container of the two most frequently occurred shapes in the microstructures globula and lamellae.

Reduction of Elastic Modulus of Titanium Alloy Ti-6Al-4V by Quenching

The use of nanoindentation techniques enhances the capabilities of qualitative analysis of elasto-plastic characteristics, especially, estimating mechanical properties of relatively small specimens in their surface layers. The results are in agreement with macromethods, which gather the information over the higher volume of the material. It was confirmed, that hardening of double phase Ti-6Al-4V alloy by quenching from beta temperatures (above beta-transus), reduces the elastic modulus by about 8 % due to increased ratio of low-modulus beta phase from 8 to 34 %.