K. Labisz

Electron Microscope Investigation of PVD Coated Aluminium Alloy Surface Layer

The purpose of this work is electron microscope investigation of the Ti/TiCN/TiAlN and Cr/CrN/CrN coatings deposited by PVD process. The investigations were performed using scanning and transmission electron microscopy for the microstructure determination. By mind of the transmission electron microscopy the high resolution and phase determination was possible to obtain. The morphology was studied as well the lattice parameters for the layer matrix and substrate phase identification using diffraction methods was applied. After the coating of the aluminium alloys AlSi9Cu and AlSi9Cu4 with the selected coatings there are crystallites detected with the size of several tenth of diameter. The investigated samples were examined metallographically using electron microscope with different image techniques, also EDS microanalysis and electron diffraction was made. As an implication for the practice a new layer sequence can be possible to develop, based on PVD technique. Some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction. The originality and value of this combination of TEM investigation for PVD deposited surface lasers on aluminium alloys makes the investigation very attractive for automotive and other industry branches. Some practical implications and employment of the surface treatment technology for elements, made from tool materials, with the PVD and CVD methods, to obtain the high wear resistant coatings, makes it possible to improve the properties of these materials by – among others – decreasing for example their friction coefficient, microhardness increase, improvement of the tribological contact conditions in practical use. One original value is it also to applied the PVD method on a common material like aluminium alloy. The double layer coatings worked out In the PVD process on the Al0Si-Cu alloys substrate hale the following configuration of the layers: bottom layer/gradient layer/wear resistant hard surface layer.

Phases and Structure Characteristics of the Near Eutectic Al-Sl-Cu Alloy Using Derivative Thermo Analysis

For determining of the micro-structural changes taking place in a near eutectic Al-Si-Cu aluminium cast alloy during heating and cooling process the UMSA device (Universal Metallurgical Simulator and Analyzer) was used. In this work the dependence between the regulated cooling speed and structure on the basis of the thermo-analysis was carried out. The thermal analysis was performed at a cooling rate in a range of 0,2 °C to 1,25 °C. The changes were examined and evaluated qualitatively by optical and electron scanning microscopy methods and the EDS microanalysis. During the investigation the formation of aluminium reach (α-Al) dendrites was revealed and also the occurrence of the α+β eutectic, the ternary eutectic α+Al2Cu+β, as well a iron and manganese containing phase was confirmed. The performed investigation are discussed for the reason of an possible improvement of thermal and structural properties of the alloy. The achieved results can be used for liquid metal processing in science and industry – for example foundry for developing and obtaining of a required alloy microstructure and properties influenced by a proper production conditions.

Laser Alloying with WC Ceramic Powder in Hot Work Tool Steel Using a High Power Diode Laser (HPDL)

Investigations include alloying the X38CrMoV5-3 hot-work tool steel surface layer with the tungsten carbide, using the high power diode laser (HPDL). The tungsten carbide ceramic particles of the medium grain size according to FSSS = 50 /m were introduced using the rotor conveyer to improve the properties of the surface layer. The powder feed rate was set at the steady level of 8.64g/min. Remelting and alloying were carried out several times in the laser power range of 1.2 – 2.3 kW in the remelting/alloying, alloying/remelting sequences. The structural mechanism was determined of gradient layer development, effect was studied of alloying parameters, gas protection method, and powder feed rate on its mechanical properties, and especially on its hardness, abrasive wear resistance, and roughness. Structure changes were revealed consisting, in particular, in its refining, and also hardness and microhardness changes in comparizon to the nonremelted steel. Examination results obtained with the EDX microanalysis, surface and linear analysis of the chemical composition, as well as the X-ray qualitative phase analysis are presented.

Structure and Properties of the 32CrMoV12-28 Steel Alloyed with WC Powder Using HPDL Laser

This paper presents the investigation results of laser alloying and the influence on structure and properties of the surface of the 32CrMoV12-28 hot work steel, carried out using the high power diode laser (HPDL). Structure changes were determined in the work, especially structure fragmentation. Also hardness investigation of the different remelting areas was performed. The reason of this work was also to determine the laser treatment parameters, particularly the laser power, to achieve good work stability and to make the tool surface more resistant for work extremal conditions. Based on microstructural examinations of the obtained material, the distribution of the reinforcing ceramic particles in the hot work tool steel was revealed. Tungsten carbide WC powder was used for alloying. The remelted layers which were formed on the surface of the investigated hot work steel were examined metallographically and analyzed using a hardness testing machine.

Additives and thermal treatment influence on microstructure of nonferrous alloys

Although Zn alloys are a very widely used material, there is a need for investigations concerning the influence of thermal conditions on its microstructure and its properties, which makes it useful for the specific tasks it has to fulfil for mass-produced items manufactured by the metalworking industry, in the automotive industry, as well as in countless electronic components. One of the possibilities is to create finer microstructures and enhance their properties, to change their chemical composition by adding alloying additives, and inoculation using modifiers. So in this paper, investigation results are presented concerning the influence of chosen alloying additives, such as Sr, Ce and Ti–B on the measured and calculated thermal characteristics and microstructure of zinc alloys with the addition of aluminium and copper. Based on the results on the phase and chemical composition of the cast Zn–Al–Cu alloys, inoculated with Sr and Ti–B, no differences were detected in the phase composition of the investigated alloys, owing to changes in cooling rates, which were chosen for the sample cooling process. A small amount of added cerium caused the occurrence of new phases present in the microstructure. Modification of the Zn–Al–Cu alloy precipitates changes in the thermomorphology of the phase and the ‘tweed’ type changes in the microstructure. Moreover, the addition of cerium causes a decrease in the temperature at the beginning (TL) and the end of the solidification, as well as the occurrence of a multicomponent eutectic, which can be detected on the derivative curve.

Structure and Properties of Diamond-Like Carbon Coatings Deposited on Non-Ferrous Alloys Substrate

With the appliance of the development of modern technologies in the areas of surface engineering and related applications, the definition of the term hard coatings can be extended by the Plasma Assisted Chemical Vapor Deposition (PACVD) method. This is a cost-effective plasma deposition process, which can be used to improve surface layer properties, e.g. hardness and wear resistance of aluminium, but also magnesium alloy parts by creating a resistant thick coating on the component surface. In this paper there have been presented results of the structure and mechanical properties investigations of crystalline diamond-like carbon gradient/monolithic coatings (Ti/DLC/DLC) deposited onto magnesium alloy (Mg-Al) and aluminium alloy (Al-Si-Cu) substrate by Plasma Assisted Chemical Vapor Deposition (PACVD). A thin metallic layer (Ti) was deposited prior to deposition of gradient coatings to improve adhesion. Microstructure investigation was performed using scanning electron microscopy and transmission electron microscopy. Tests of the coatings adhesion to the substrate material were made using the scratch test. As an implication for the practice a new layer sequence can be possible to develop, based on PACVD technique. Wear test were performed using the ball-on-disk method.

Wrought aluminium–magnesium alloys subjected to SPD processing

Abstract The article presents the influence of stationary plastic deformation, using the equal channel angular pressing (ECAP) method, on the structure and properties of an aluminium alloy with 3 % magnesium content. In order to investigate changes in the structure and substructure, light microscopy and transmission electron microscopy were used. The influence of plastic deformation was determined by hardness measurement using the Vickers method. The results of the investigation show that, even after one ECAP, it is possible to decrease grain size to a range of 30 – 70 nm, and increase the mechanical properties by nearly 90 %. It was also found that the additional twist angle of the die has a minor effect on the properties and structure of the investigated alloy.

Characterisation and properties of hybrid coatings deposited onto magnesium alloys

Abstract This paper presents the research results of the physical vapour deposition and chemical vapour deposition surface treatment performed on samples of heat treated cast magnesium alloy as well as the modelling of properties of the obtained coatings using the finite element method. Ti/Ti(C, N)/CrN, Ti/Ti(C, N)/(Ti, Al)N, Ti/(Ti, Si)N/(Ti, Si)N, Cr/CrN/CrN, Cr/CrN/TiN and Ti/DLC/DLC coatings were investigated. Based on fractographic investigations, it was found out that the applied coatings are characteristic of mono-, di- or multilayer structure according to the applied layer system. The individual layers are deposited uniformly and adhere tightly to the substrate and to each other. The coatings reveal a dense cross-sectional morphology as well as good adhesion to the substrate. The critical load LC2 was measured within the range of 11–19 N, depending on the coating type. The results obtained from numerical analysis performed using a mathematical model have enabled full integration of material engineering knowledge and informatics tools.

Comparison of Mechanical Properties of the 32CrMoV12-28 Hot Work Tool Steels Alloyed with WC, VC and TaC Powder Using HPDL Laser

This work presents the investigation results of laser remelting and alloying especially the laser parameters and its influence on the structure and properties of the surface of the 32CrMoV12-28 hot work steel, using the high power diode laser (HPDL). As a result structure changes in form of fragmentation were determined. The reason of this work was to determine the optimal laser treatment parameters, particularly the laser power to achieve good layer hardness for protection of this hot work tool steel from losing their work stability and to make the tool surface more resistant to action in hard conditions. For alloying the tantalum carbide, tungsten carbide and vanadium carbide powders were used. For investigations hardness measurements of the different remelting areas were performed. The remelted layers which were formed in the surface of investigated hot work steel were examined metallographically and analyzed using light and electron microscope. Three phases of carbides, TaC, VC and WC, were observed.

Modelling of properties of the alloy tool steels after laser surface treatment

This paper presents the investigation results of the computer modelling of the surface layer hardness of hot work tool alloy steel alloyed with the ceramic powders using the High Power Diode Laser (HPDL). Laser treatment by remelting or alloying with the carbides was employed for improvement of the surface layer properties of tools made from the hot work tool steels. The developed model of the neural network make predicting possible for the surface layer hardness values. Further investigations should be concentrated on computer modelling of microhardness and resistance wear abrasion using the artificial neural networks. The surface layer of the hot work steel alloyed with ceramic powder using the HPDL have good properties and makes it possible for using in various technical and industrial applications. The artificial neural networks were used to determine the technological effect of laser alloying on hardness of the hot work tool steels. [Received 10 January 2007; Accepted 12 July 2007]