K. Gołombek

Investigation of the structure and properties of coatings deposited on ceramic tool materials

This paper presents the results of the investigation of the structure and properties of the coatings deposited with the PVD and CVD techniques on sintered tool materials: cermets, oxide Al2O3 ceramic and nitride Si3N4 based ceramics. The investigation includes the metallographic analysis using the transmission and Scanning Electron Microscope (SEM), chemical composition analysis, as well as the analysis of the mechanical and functional properties of the material. Tests were carried out on the multipoint inserts made from the ceramic tool materials based on Al2O3 and Si3N4 and cermets, both uncoated and coated with gradient, multicomponent and multilayer hard wear resistant coatings with PVD and CVD processes.

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.

Structural Characteristics of the Modern Sintered Tool Materials

Within the project framework the structure and properties was investigated of the cemented carbides, cermets and oxide ceramics using the scanning electron microscope (SEM). The X-ray qualitative microanalysis and surface distribution analysis of elements in the investigated materials were made using the EDS X-ray energy dispersive radiation spectrometer. The roughness measurements of the developed materials were made in two orthogonal directions. The Ra parameter was assumed to be the value describing surface roughness. The microhardness tests using the Vickers method were made on the dynamic ultra microhardness tester. The measurements were made in the „load - unload” mode.

Structure and Properties of Aluminum Matrix Composites Reinforced by Al2O3 Particles

The work presents the research results of modern composite materials. The matrix material was EN AC AlSi12 alloy while the reinforcement ceramic preforms, obtained through sintering process of Al2O3 Alcoa CL 2500 powder with addition of carbon fibers as pore forming agent burned out during sintering. The composites were produced with use of porous material pressure infiltration method. The main limitation of base technology is a difficulty in obtaining composite materials with volumetric participation of ceramic phase in amount not less than 20%. Obtained on the base of ceramic preforms composite materials were tested with scanning electron microscopy. Additionally, hardness and tensile test was performed for acquired materials. Achieved results indicate the possibility of producing, with use of pressure infiltration method, porous preforms composed of Al2O3 particles, new composite material with desired microstructure and properties, being a cheaper alternative for materials with base of ceramic fibers.

Structure and properties of selected cemented carbides and cermets covered with TiN/(Ti,Al,Si)N/TiN coatings obtained by the cathodic arc evaporation process

This study presents the results of microstructural examinations, mechanical tests and service performance tests carried out on thin TiN/(Ti,Al,Si)N/TiN wear resistance coatings obtained by the CAE process on cermet and cemented carbide substrates. Microstructural examinations of the applied coatings and the substrate were made with an OPTON DSM 940 SEM and a LEICA MEF4A light microscope. Adhesion of the coatings on cemented carbides and cermets was measured using the scratch test. The cutting properties of the materials were determined from service tests in which continuous machining of C45E steel was carried out. The hardness of the substrate and the microhardness of the coatings were determined with a DUH 202 SHIMADZU ultra microhardness tester with a load of 70 mN. Roughness tests were also carried out before applying the coatings and after the PVD process. Cutting tests confirmed the advantages of the TiN/(Ti,Al,Si)N/TiN type coatings obtained using the PVD method in the CAE mode on cemented carbides and cermets, as a material that undergoes very low abrasive, thermal and adhesion wear. These coatings extend tool life compared to commercially available uncoated tools with single and multi-layer coatings deposited using PVD/CVD methods.

Role of Halloysite Nanoparticles and Milling Time on the Synthesis of AA 6061 Aluminium Matrix Composites

The aim of this work is to determine the effect of a reinforcing phase and manufacturing conditions on the structure and properties of newly developed nanostructural powders of composite materials with the aluminium alloy matrix reinforced with natural halloysite nanotubes. Composite materials were manufactured employing as a matrix the air atomized powders of AA 6061 aluminium alloy and as a reinforcement the halloysite nanotubes. Composite powders of aluminium alloy matrix reinforced with 5, 10 and 15 wt.% of halloysite nanotubes were fabricated by high-energy mechanical alloying using a planetary mill. Elaborated composite powders were characterized for their apparent density, microhardness, particle size distribution and microstructure. A structure of newly developed nanostructured composite materials reinforced with halloysite nanotubes prove that a mechanical alloying process allow to improve the arrangement of reinforcing particles in the matrix material. A homogenous structure with uniformly arranged reinforcing particles can be achieved by employing reinforcement with halloysite nanotubes if short time of mechanical alloying is maintained thus eliminating an issue of their agglomeration.

Structure and Properties of the Multicomponent and Nanostructural Coatings on the Sintered Tool Materials

This chapter presents a general characteristic of sintered tool materials, in particular sintered sialons, nitride ceramics, injection-moulded ceramic-metallic tool materials and cemented carbides and a general characteristic of their surface treatment technology and especially chemical vapour deposition (CVD) and physical vapour deposition (PVD) techniques. The results of our investigations in technology foresight methods concerning the development prospects of surface engineering of sintered tool materials are presented. In the next subsection, we discuss the outcomes of multifaceted research carried out with advanced materials engineering methods, including high-resolution transmission electron microscopy, into the structure and properties of multicomponent, graded and multilayer coatings on the investigated tool materials, including the newly developed injection moulded ceramic-metallic tool materials. Special attention was drawn to a one-dimensional structure of the studied PVD and CVD coatings and its impact on the properties of coatings.

Physical Simulation of Thermomechanical Processing of Multiphase Mn-Al Steels with Retained Austenite

The thermomechanical processing of certain AHSS still represents a challenge due to the lack of complete data on their hot deformation behaviour. Therefore, the aim of this study was to provide data on the hot-working behaviour of four model steels of the type 0.17C-3Mn-1.5Al and 0.17C-5Mn-1.5Al with or without Nb microaddition. The paper presents the results of hot strip rolling simulated by multi-step compression tests using a Gleeble simulator. Analysis of microstructural features of steels with focusing on Mn and Nb contents was carried out using X-ray, LM (light microscopy) and SEM (scanning electron microscopy). It has been shown that the applied deformation schedule allows to develop very fine-grained transformation products of supercooled austenite and controlled cooling with isothermal holding at 400°C enables to retain from 13 to 18% of retained austenite with the blocky or lath-type morphology. Mn alloying in the amount of 3 to 5 wt.% does not affect hot deformation resistance contrary to Nb microaddition, which raises flow stress levels. Influences of Mn and Nb on the retained austenite content and its carbon content are discussed.