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We studied fine oscillatory structure (FOS) appearing on the rising slope of the current peak in resonant tunneling diodes. FOS is a manifestation of the quantum interference caused by reflection of a part of electron wave transmitted through the double barrier at an internal interface. We conclude that FOS was frequently observed in the past but was incorrectly attributed to the lateral quantization of the quantum-well states.

This paper presents the effect of the deposition parameters on the properties of the Ti+TiN, Ti+Ti(C x N x −1 ), and Ti+TiC two-layer surface coatings obtained using magnetron sputtering in a vacuum furnace with a controlled temperature on a sintered ASP 30 high-speed matrix. Results of the investigated coatings’ tests are presented, depending on the working atmosphere, distance from the magnetron shield, and vacuum furnace temperature. Their effect on the structural and mechanical properties of the coatings has been evaluated.

Results of investigations are presented of structure and mechanical properties, as well as of the comparative tests of thermal fatigue resistance of the heat-treated multi-component Cr–Mo–W–V steels, assigned for the hot-work tools. It was found out that the investigated 47CrMoWVTiCeZr16-26-8 steel demonstrates higher mechanical properties than the X40CrMoV5-1 steel, however, it has lower impact strength and a similar thermal fatigue resistance.

The paper reviews, from author’s experience, the heat treatment technology, thermo-chemical treatment and PVD coating process of high-speed steels and the accompanying phase transformations. Structure of the cases and coatings formed on tools, resulting from various thermo-chemical and PVD processes, and working capabilities of tools after thermo-chemical treatment and coated in the PVD process are compared.

This paper presents an on-line tracking optimization scheme for sensor guided robotic manipulators by associating sensor information, manipulator dynamics and a path generator model. Feedback linearization-decoupling permits the use of linear SISO prediction models for the dynamics of each robot joint. Scene interpretation of CCD-camera images generates spline fitted segments of future trajectory. In the sensor vision field the proposed optimization criteria minimizes the error between state variables of the prediction model and the state variables of the spline trajectory generator. These techniques, allied with separation of disturbance rejection and path-tracking performance by the proposed feed-forward following model predictive (FMP) servo-controller design, permits very high path tracking dynamics (and consequently small errors). Experimental results on implementation of a CCD-camera guided hydraulic robot and a welding robot demonstrates the practical relevance of the proposed approach.

The paper presents the results of research on the possibility of application of cobalt addition in concentration of up to 5% for the W-Mo-V and W-V high-speed steels of the 9-2-2, 11-2-2 and 11-0-2 types with economically designed chemical composition and the concentration of Si increased to about 1% of W reduced to 9–11% and concentration of Mo limited to about 2%. It was found out that cobalt in the concentration limited to about 5% results in increasing the secondary hardness effect by 1.6–1.9 HRC, depending on a grade of steel. The reason for the secondary hardness effect is the precipitation of dispersive carbides of the M 4 C 3 type in the matrix of the tempered martensite and martensite transformation of the retained austenite, which occurs during cooling from tempering temperature. The maximum secondary hardness effect about 66.3–67.6 HRC, depending on a grade of steel, increases the hardness by about 2–4 HRC, compared with the hardness in the as-quenched state, and occurs in each steel after tempering at 540°C and austenitizing at 1240°C during 100 s. The higher hardness, which is the characteristic of cobalt steel, is also caused by strengthening the martensitic matrix by cobalt, tungsten and molybdenum in these steels, in which the mentioned elements are present. It was also proved that 5% cobalt addition decreases the primary austenitic grain size and reduces the volume fraction of the retained austenite after quenching and tempering. The 5% cobalt addition results in enhancing the working properties of tools, longer tool life and makes it possible to increase cutting speed by about 50%, compared with the steels of identical concentration of other alloying elements but without cobalt addition. In the investigated steels, however, cobalt does not have any significant influence on erosion resistance, which is independent of the steel hardness after quenching and tempering.

This paper presents the results of investigations regarding the phase transformations occurring during the heat treatment of W-Mo-V + Si + Nb high-speed steels. It was found that investigated steels demonstrate their maximum secondary hardness, about 66 HRC, in connection with the precipitation of M 4 C 3 carbides in tempered martensite after austenitizing at 1240°C and tempering at 540–570°C. The paper presents also results of investigations regarding the erosion resistance of TiN and Ti(C,N) PVD coatings deposited on the investigated steels. TiN and Ti(C,N) coatings deposited in the PVD process yield, respectively, three and seven times greater erosion resistance of the steel surface and demonstrate good adhesion to the investigated steels forming the substrate. Quantitative metallography methods as well as mass loss and created craters 3-D measurements were employed to evaluate the erosion resistance of the investigated coatings. It was found that the surface topography influences the erosion resistance of PVD vacuum arc method coatings. The investigated coatings are not affected by the type of the substrate high-speed steels.

The paper presents a method of designing the chemical composition of constructional alloy steels based on the required Jominy hardenability curve shape and using neural networks. It presents a new method for the modelling of hardenability curves according to the chemical composition of the steel. Using this approach, a further method was developed—the method of designing of the chemical composition of the steel showing the required properties, including the required hardenability. Both methods are presented in the paper, as well as exemplary calculations using the computer tools developed.

The paper presents mechanical properties of two kinds of Co-based and one Fe-based metallic ribbons by the depth sensing indentation (DSI) technique. Investigations were carried out on two kinds ternary alloy Co 77 Si 11,5 B 11,5 and Fe 78 Si 13 B 9 and multicomponent Co 68 Fe 4 Mo 1 Si 13,5 B 13,5 , which are so-called “zero-magnetostriction” materials. Metallic ribbons were investigated in amorphous state and partially crystallized state after annealing in 400°C in argon atmosphere. Heating of ribbons obtained by melt spinning technique was performed to check its effect on changes of mechanical properties.

The paper presents the results of the investigation of the front contact manufactured using silver pastes (based on experimentally prepared silver powder) on monocrystalline silicon solar cells in order to reduce contact resistance. Various deposition and fabrication techniques were applied to improve the electrical properties of contacts. The aim of the paper was to apply an unconventional method (selective laser sintering) to improve the quality of forming contacts of silicon solar cells. The topography of both the melted/sintered contact and textured silicon was investigated using atomic force microscopy. Resistance of front electrodes was measured using the Transmission Line Model (TLM). Both surface topography and cross section of front contacts were researched using the scanning electron microscopy.

This chapter presents the theoretical basis concerning the broad possibilities offered by the contemporary applications of artificial intelligence tools, especially artificial neural networks in the field of material engineering. The examples of own research pursued at the Institute of Engineering Materials and Biomaterials of the Silesian University of Technology, including the modeling and simulation of different properties of engineering materials, are presented. Discussed separately is a pioneering project of implementing artificial neural networks in order to predict the development trends of materials surface engineering.

This chapter presents results from investigations about high-manganese austenitic steels, which have gained increasing importance over the recent two decades. Intense research into this group of steels indicates the need for employing them in the global automotive sector, especially for constructional components of cars absorbing impact energy in road collisions. The examples of extensive research over this group of high-manganese austenitic steels have been pursued by the authors at the Division of Materials Processing Technology, Management and Computer Techniques in Materials Science, the Institute of Engineering Materials and Biomaterials of the Silesian University of Technology, Gliwice, Poland. The essence of the research concerns the designing of thermo-mechanical processing of selected high-manganese austenitic steels with carefully selected but diversified chemical composition in order to refine their structure and improve mechanical properties. Thermo-mechanical processing was performed using a thermo-mechanical simulator DSI (Dynamic System Inc.) Gleeble 3800. The results of the investigations performed with the DSI simulator allowed to design different variants of hot rolling consisting of several stages for the investigated high-manganese austenitic steels. Different processes controlling the curve of strain hardening could be used by applying the varied conditions of thermo-mechanical processing, and especially a diversified degree of deformation and isothermal heat treatment after finishing plastic working, such as dynamic recovery, dynamic recrystallization, and static recrystallization.

The aim of the paper was to apply the newly developed instruments ‘Corescan’ and ‘Sherescan’ in order to measure the essential parameters of producing solar cells in comparison with the standard techniques. The standard technique named the Transmission Line Method (TLM) is one way to monitor contacting process to measure contact resistance locally between the substrate and metallization. Nowadays, contact resistance is measured over the whole photovoltaic cell using Corescanner instrument. The Sherescan device in comparison with standard devices gives a possibility to measure the sheet resistance of the emitter of silicon wafers and determine of both P/N recognition and metal resistance. The Screen Printing (SP) method is the most widely used contact formation technique for commercial silicon solar cells. The contact resistance of manufactured front metallization depends of both the paste composition and co-firing conditions. Screen printed front side metallization and next to co-fired in the infrared conveyor furnace was carried out at various temperature from 770°C to 920°C. The silver paste used in the present paper is commercial. The investigations were carried out on monocrystalline silicon wafers. The topography of co-fired in the infrared belt furnace front metallization was investigated using the atomic force microscope and scanning electron microscope (SEM). There were researched also cross sections of front contacts using SEM microscope. Front contacts of the solar cells were formed on non-textured silicon surface with coated antireflection layer. On one hand, based on electrical properties investigations using Sherescan instrument it was obtained the knowledge of the emitter sheet resistance across the surface of a wafer, what is essential in optimizing the emitter diffusion process. On the other hand, it was found using Corescan instrument that the higher temperature apparently results in a strongly decreased contact resistance.

The paper presents comparison of results of investigations into phase transformation in WMoVCo type 11-0-2-5 and WMoV type 11-0-2 high-speed steels. The maximum hardness respectively 66 HRC and 64.5 HRC investigated steels have after quenching at the temperature of 1240°C and tempering at the temperature of 540°C. Secondary hardening in these steels is due mainly to precipitation of fine M4C3 carbides and also to martensitic transformation of retained austenite into α phase.

Evaluation has been made of the consistency of calculation of the hardenability curves of the selected heat-treatable alloyed constructional steels with the experimental data. The study has been conducted basing on the analysis of present state of knowledge on hardenability calculation employing the neural network methods. Several calculation examples and comparison of the consistency of calculations for various calculation methods employed are included.

It was found that about 0.5% Nb or 0.3% Ti may be employed as partial substitutions for vanadium in the W Mo V high-speed steels of the 11-0-2, 11-2-2 and 9-2-2 types, with concentration of Si increased to 0.7%. Additions of niobium or titanium introduced into these steels result in change of the chemical compositions of the MC type primary carbides. This makes possible transition of vanadium, in a sufficient concentration, into the solid solution, and obtaining the secondary hardness effect not lower than in the steels without niobium or titanium, even with lower vanadium concentration in the steel. Additions of the 0.5% Nb or 0.3% Ti secure the highest secondary hardness of about 66 HRC in the investigated steels. The main reason of the secondary hardness effect in the investigated steels with the additions of niobium or titanium is dispersive precipitation of the M 4 C 3 carbides in the tempered martensite matrix and the martensitic transformation of the retained austenite.

The paper concerns investigation of nanocrystalline composites technology preparation. The composites in the form of rings with rectangular transverse section, and with polymer matrix and nanocrystalline metallic powders fulfillment were made, for obtaining good ferromagnetic properties. The nanocrystalline ferromagnetic powders were manufactured by high-energy ball milling of metallic glasses strips in an as-quenched state. Generally for investigation, Co matrix alloys with the silicon polymer were used. Magnetic properties in the form of hysteresis loop by rings method were measured. Generally composite cores showed lower soft ferromagnetic properties than winded cores of nanocrystalline strips, but composite cores showed interesting mechanical properties. Furthermore, the structure of strips and powders on properties of composites were investigated.

The paper presents the conception of a structure of a system, being under development now, aimed at forecasting of the residual life of the elements of power plants′ installations. The evaluation system worked out until now includes the following procedures: • - procedures for assessment of usefulness for further work of components being subjected to pressure based on parameters both calculated and real ones along with the standard material data, • - general procedure of forecasting the life of elements working in creep conditions, • - detailed procedure of selection and carrying out of metallographic examining aimed at assessment of wear and damage of elements working in creep conditions, • - procedures for selected metallographic inspections being employed in diagnostics of elements working in creep conditions, Four interfaces have been designed, one of which is a user interface and the other three ones are dedicated for contacting the database. The materials' database contains the standard material data characteristic for a given steel, including mainly characteristic properties of materials dependent on the parameters of work. A communication interface is employed for contacting the materials' database each time the metallographic forecast is being evaluated by the system. The knowledge acquisition interface is being employed for collecting new data and is being used only by the expert in the field of creep for data auditing purposes or for appending the database with the new data. Another database with the results of the metallographic examinations is constantly modified as the subsequent routine tests are carried out and is record of history of degradation of a power installation in question. The system being developed, having access to many materials' data, may prove useful for forecasting of the residual life of the elements of the power installations and for designing the power installations.

This paper presents the results of investigations into the role of Si as an alloying element in the high-speed steels without molybdenum. The examinations were carried out on tungsten-vanadium high-speed steels of the 9-0-2+Si type with Si contents of 0.3–5% and 1.05% C, 9.5% W, 2.5% V and 4.5% Cr. It was found that Si many be employed as an alloying element in such high-speed steels replacing to some extent other alloying elements. Steels containing 1–2% Si quenched at 1200–1210°C and tempered twice at 510–540°C have hardness values of about 63 HRC and bending strength of 2000–2500 MPa and may be used for cutting tools that have very good cutting properties after coating with wear resistant layers in the PVD process.

Experience gained by a team of researchers developing a database system designed as an aid for engineers and students who work out the tools made from the high-speed steels shows that this sort of system needs a flexible yet powerful user interface. To solve this task a front-end expert system module is being designed. Present design parameters assume that the intelligent add-on shall consist of some 500÷1000 rules enabling the user to compare the characteristics properties of various high-speed steels in respect to given applications, more, the technology generating module shall include the what-if option. To make all these new features as user friendly as possible it has been decided that the work should start with development of the linguistic task-oriented processor to enable the user to contact with the system in a subset of the natural language. To this end a prototype of a user interface was written in PROLOG and is presently being tested. In order to set the limits to the above mentioned task the dictionary was developed including all the necessary nouns, verbs, adjectives, numerals and sentence structures that are allowed to appear in the interface domain specific language.

The paper presents results of investigations into phase transformations in WMoV 11-2-2 high-speed steels with a part of vanadium substituted with niobium or titanium. The optimum combinations of 0.5% Nb or 0.3% Ti with 1.6% V gave maximum hardness of 65.5–66 HRC after tempering at 570 and 540°C, respectively. In all steels covered by the study secondary hardening was due chiefly to precipitation of fine M4C3 carbides in martensite and martensitic transformation of retained austenite into α phase.

A review is presented of author's works in the field of high-speed steels including optimizing of chemical composition, effects of metallurgical factors, phase transformations, heat treatment, thermo-mechanical, thermo-chemical and surface treatments and computer-aided techniques for selection of high-speed steels for tools and development of heat treatment and thermo-chemical treatment procedures.

The paper presents an idea of a structure of a system for forecasting of service life and residual life of power installations' components subjected to pressure. The system proposed is based on two databases, the basis for calculations is the materials' database whereas the metallographic examinations' results database is being employed only for storing the results of computations featuring thus the record of history of degradation of a given power installation. On account to many materials' characteristic data the system may prove very useful for designing and exploitation of power machinery.

The results from clinical tests of single implant-retained dentures (SIDs) are quite promising. However, the biomechanics of SIDs are still insufficiently determined. The aim of the study was to compare the implant loads and pressures beneath one and two implant-retained dentures (TIDs) under oblique mastication forces. The finite element method was used to conduct a model analysis in order to compare loading of the denture attachment onto the implant that accompanies oblique mastication forces in the cases of SIDs and TIDs. The possibility of a denture detaching and sliding on the mucous membrane surface was simulated. The SID solution faced a more remarkable tilt in the direction of the mastication forces, a higher pressures on the mucous membrane surface, and higher implant loadings. The hingelike restraints in the TID favored utilization of the support in the posterior area. The higher pressure values for the SID can be confusing and could lead to inaccurate conclusions about the acceptability of the SID. In the TID, the same areas of the mucous membrane were persistently loaded, independent of the occlusal force direction. In contrast, in the SID the full freedom of rotational movement enhances alternating use of the mucous membrane. This finding explains the more frequent sores in the mucous membrane beneath the TID than beneath the SID.

The research issues concerning the production of coatings are the most important directions of surface engineering development, ensuring the obtainment of coatings of high usable properties in the scope of mechanical characteristics and corrosion resistance (Yu et al., 2009; Cheng et al., 2009; Kao, 2009; Mao et al., 2009; Sundararajan et al., 2009). Giving new operating characteristics to commonly known materials is frequently obtained by laying simple monolayer, multilayer or gradient coatings using PVD methods (Dobrzanski et al.,2005; Lukaszkowicz & Dobrzanski, 2008). While selecting the coating material, we encounter a barrier caused by the fact that numerous properties expected from an ideal coating are impossible to be obtained simultaneously. For example, an increase in hardness and strength causes the reduction of the coating’s ductility and adherence to the substrate. The application of the nanostructure coatings is seen as the solution of this issue (Voevodin et al., 2005; Yang et al., 2007). According to the Hall–Petch equation, the strength properties of the material rise along with the reduction of the grain size. In case of the coatings deposited in the PVD processes, the structures obtained with grain size ~10 nm cause the obtainment of the maximum mechanical properties. Coatings of such structure present very high hardness >40 GPa, ductility, stability in high temperatures, etc. (Tjong & Chen, 2004; Zhang et al., 2007; Veprek et al., 2005). The known dependency between the hardness and abrasion resistance became the foundation for the development of harder and harder coating materials. The progress in the field of producing coatings in the physical vapour deposition process enables the obtainment of coatings of nanocrystal structure presenting high mechanical and usable properties. The coatings of such structure are able to maintain a low friction coefficient (selflubricating coatings) in numerous working environments, maintaining high hardness and increased resistance (Donnet & Erdemir, 2004; Voevodin & Zabinski, 2005). The main concept in the achievement of high hardness of nanostructure coatings and good mechanical properties and high strength related to it, particularly in case of nanocomposite coatings (Holubar et al., 2000; Rafaja et al., 2007; Carvalho et al., 2004), is the restriction of

For the reason of growing requirements for materials made from light alloys concerning mechanical properties, corrosion resistance, manufacturing costs and the influence of the environment this efforts can be consider as very up-to-date from the scientistic view and very attractive for investigation. The rising tendencies of magnesium alloy production, show increased need of their application in world industry and what follows the magnesium alloys become one of the most often apply construction material our century. A contemporary technological development makes it necessary to look for new constructional solutions that aim at the improvement of the effectiveness and quality of a product, at the minimization of dimension and mass as well as the increasing of reliability and dimension stability in the operation conditions. For a dozen or so years one can observe a rising interest in the non-ferrous metals alloys including magnesium alloys which are an examination subject in many research and university centres in the country and abroad as well as in major manufacturers of mechanical engineering industry, chemical, power, textile, electronic, paper and aeronautic industries and in particular automotive, shipbuilding, aircraft, sports and even nuclear industries (Baker, 1999; Dobrzanski and Tanski, 2009; Fajkiel and Dudek, 2004). Magnesium alloys which are successfully used for a long time in different industry branches are a combination of low density and high strength. The above features together with low inertia have significantly contributed to the wide use of magnesium alloys in fast moving elements, in locations where rapid velocity changes occur and in products in which lowering a final mass of a product is required. The greatest interest in magnesium alloys was shown and is still shown by an automotive industry (Figure 1) (Horst and Mordike, 2006; Kainem, 2003; Tanski et al., 2007). For example, General Motors in their big cars (Savana

The significant variety of high-speed steels makes the problem of their proper usage very important. To this end a system has been developed to assist the synthesis of the proper technology for high-speed steels. The system offers assistance for numerous classes of users including manufacturing engineers designing new manufacturing processes, tool designers, scientific workers and students, etc. The system is a flexible one, being designed so that in future it may contain data about other classes of materials as well: the data acquisition and presentation module may be left intact. The system in its present state contains two sub-systems, the root system employed to handle the data being accessed by either of the dedicated sub-systems, in this case by the high-speed steels sub-system. The problem of selection of the proper high-speed steel for a given application lies in the abundant number of their makes, differing properties and relatively complex heat and thermochemical treatment. The problem of a proper selection of the right steel for a given tool is only partially solved by choosing one with apparently adequate properties, as they may not be obtained if the proper technology should not be employed. Numerous aspects of tool design influence the tool technology, making it impractical to use heat treatment and thermochemical treatment data extracted simply from the appropriate tables. Deep knowledge of the properties of the high-speed steels and of the conditions for their proper usage — being intricately interdependent — is not common amongst their users so that guidance in this field is imperative. The system enables a user to obtain information about the properties of all of the makes of steel available and about their applicability for given classes of tasks. It is possible to synthesise a proper heat treatment technology for a steel chosen to make a given tool. Several classes of system printouts are built in.

This investigation of the influence of high temperature thermo-mechanical treatment (HTTMT) involved 20 ∼ 60% deformation in the temperature range of 1000 ∼ 1150°C or conventional heat treatment (CHT), and examination of the phase transformations, the structure and the properties of W-Mo-V high-speed steel. The HTTMT, comprising austenitizing at 1190°C, drop forging at 1000 ∼ 1150°C and tempering at 540°C, may be employed for making particular tools from 12−0−2+C high-speed steel. The method can be recommended for the manufacture of parts of gear-cutting hobs. It is possible also to use HTTMT for parting-off tools and other high-speed steel tools of simple geometrical shapes. The method, with deformation by hot rolling, is suitable for the manufacture of twist drills, which are usually hot rolled. After HTTMT, as in the case of CHT, the structure of 12−0−2+C steel consists of fine lath martensite twinned in some regions, precipitations of cementite, retained austenite and undissolved M 4 C 3 and M 6 C carbides. In the martensite of the steel after the HTTMT, apart from the cementite there are fine M 4 C 3 carbides, increasing the hardness with respect to CHT. The HTTMT of this steel at 1150°C caused refinement of the austenite grain by dynamic or metadynamic recrystallization of austenite, finally resulting in refinement of the martensite laths. After HTTMT carried out at 1000°C, the austenite grains were elongated and their size was similar to that after CHT. The martensite laths had an irregular bent shape caused by dynamic recovery and polygonization of the austenite. Tempering of the steel both after HTTMT and after CHT caused autonomous precipitation of fine M 4 C 3 carbides during holding at the tempering temperature with a consequent secondary hardening effect, which was also influenced by martensitic transformation of retained austenite during cooling from the tempering temperature. After CHT a secondary hardness of 66.5 HRC was produced on tempering at 570°C. HTTMT caused the temperature of the maximum secondary hardness of 63 ∼ 65 HRC to shift to 540°C. Other properties after HTTMT were similar to those produced by CHT.

The laser surface remelting (LSR) process was successfully applied to restore localized corrosion resistance in sensitized stainless steel and also as a useful method to improve passivity of some martensitic stainless steels. The LSR process can be successfully applied to repair cracks and defects at the surface of highly thermo-mechanically loaded parts of stainless steel. The purpose of presented study was to evaluate the microstructure and properties of laser remelted surface of stainless steels. The wrought austenitic stainless steel and sintered in vacuum 316L type were studied. The laser treatment was performed with the use of high power diode laser (HPDL) and the influence of beam power of 0.7-2.1kW on the properties of the surface layer was evaluated. The geometrical characteristics and x-ray analysis of weld bead were studied as well as microhardness, surface roughness and corrosion resistance were measured. The increase of laser beam power of LSR resulted in the increase of hardness of sintered stainless steel due to the reduction of porosity and formation of fine dendritic and cellular-dendritic microstructure. The corrosion resistance of remelted surface increased for sintered materials, when remelted at 2.1kW. The wrought stainless steel revealed impairment of pitting corrosion when remelted at lower beam power rate.

This work presents mechanical properties and corrosion resistance of duplex stainless steels obtained through powder metallurgy starting from austenitic X2CrNiMo17-12-2 (AISI 316L), martensitic X6Cr13 (AISI 410L) powders by controlled addition of alloying elements in the proper quantity to obtain the chemical composition of the structure similar to biphasic one. In the mixes preparations the Schaffler’s diagram was taken into consideration. Prepared mixes of powders have been sintered in a vacuum furnace with argon backfilling. After sintering rapid cooling was applied using nitrogen. Produced duplex stainless steels have been studied by SEM with EDS and light optical microscopy (LOM) and X-rays analysis to determine obtained structures. Corrosion properties have been studied through electrochemical methods in 1M NaCl.

This work presents corrosion resistance results of duplex stainless steels obtained through powder metallurgy starting from austenitic X2CrNiMo17-12-2 (AISI 316L), martensitic X6Cr13 (AISI 410) powders by controlled addition of alloying elements in the right quantity to obtain the chemical composition of the structure similar to biphasic one. In the mixes preparations the Schaffler's diagram was taken into consideration. Prepared mixes of powders have been sintered in a vacuum furnace with argon backfilling. After sintering rapid cooling was applied using nitrogen under pressure. Produced duplex stainless steels have been studied by SEM with EDS and light optical microscopy and X-rays analysis to determine obtained structures. Corrosion properties have been studied through electrochemical methods in 1 M NaCl.

This paper presents corrosion resistance results in salt fog spray test of duplex stainless steels obtained through powder metallurgy starting from austenitic X2CrNiMo 17-12-2, martensitic X6Cr13 powders by controlled addition of alloying elements in the right quantity to obtain the chemical composition of the structure similar to biphasic one. In the preparations of mixtures the Schaffler's diagram was taken into consideration. The prepared mixtures of powders have been sintered in a vacuum furnace with argon backfilling. After sintering two different cooling cycles were applied: rapid cooling with an average cooling rate of 245 °C/min using nitrogen under pressure 0.6 MPa and slow cooling with furnace with an average cooling rate of 5 °C/min in argon atmosphere. The corrosion properties have been studied through salt fog spray test which is applied by the automotive industry end-users because it reproduces the behaviour of a material in front of the environmental corrosion with feasibility. According to the achieved results, it was confirmed that the applied sintering method as well as powder mixtures preparation allows for manufacturing the sintered duplex steels with good corrosion properties in chloride environment.

This paper presents the results of laser treatment influence on structure and properties of the surface of the X40CrMoV5-1 hot work tool steel, using the high power diode laser (HPDL) for remelting and alloying. In this work structure changes as well as hardness and roughness are investigated. The goal of this work was also to determine technological conditions for remelting of surface layer with HPDL laser.This paper presents the results of laser treatment influence on structure and properties of the surface of the X40CrMoV5-1 hot work tool steel, using the high power diode laser (HPDL) for remelting and alloying. In this work structure changes as well as hardness and roughness are investigated. The goal of this work was also to determine technological conditions for remelting of surface layer with HPDL laser.

The following review paper is a synopsis of the fundamentals of laser remelting and alloying, outlining some of its benefits compared with conventional heat treatment techniques of hot-work tool steel X40CrMoV5-1. A selective review of the experimental research carried out in this area is presented. The aim of such treatment was to harden and alloy the steel surface which had been previously coated with the paste consisting of the tungsten carbide and the inorganic binder. Development of the surface layer was observed in which one can distinguish the remelted zone, heat-affected zone and the transient zone. Occurrences of the un-melted tungsten carbide grains were observed in the structure and the increased tungsten content compared to the native material, whose variable concentration is connected with the molten metal fluctuation in the pool during alloying. The fine grained, dendritic structure occurs in the remelted and alloyed zone with the crystallization direction connected with the dynamical heat abstraction from the laser beam influence zone. It has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones.The following review paper is a synopsis of the fundamentals of laser remelting and alloying, outlining some of its benefits compared with conventional heat treatment techniques of hot-work tool steel X40CrMoV5-1. A selective review of the experimental research carried out in this area is presented. The aim of such treatment was to harden and alloy the steel surface which had been previously coated with the paste consisting of the tungsten carbide and the inorganic binder. Development of the surface layer was observed in which one can distinguish the remelted zone, heat-affected zone and the transient zone. Occurrences of the un-melted tungsten carbide grains were observed in the structure and the increased tungsten content compared to the native material, whose variable concentration is connected with the molten metal fluctuation in the pool during alloying. The fine grained, dendritic structure occurs in the remelted and alloyed zone with the crystallization direction connected with the dynamical heat a...

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.

This work presents the possibility of obtaining duplex stainless steels through powder metallurgy technology starting from austenitic X2CrNiMo17-12-2, martensitic X6Cr13 powders by controlled addition of alloying elements, such as Cr, Ni, Mo, Cu in the right quantity to obtain the chemical composition of the structure similar to biphasic one. Moreover the ferritic stainless steel X6Cr17 has been mixed to austenitic stainless steel in the ratio of 50%-50% in order to exam the deriving structure after sintering. In the studies behind the preparation of mixes, Schaffler’s diagram was taken into consideration. Prepared mixes of powders have been compacted at 800 MPa and sintered in a vacuum furnace with argon backfilling at 1260°C for 1 hour; after sintering rapid cooling has been applied in N2.

The objective of the present work was to study the modification of the microstructure of hot-work tool steels X40CrMoV5-1 and X38CrMoV5-3 during the surface modifying by means of laser technology. The aim of such treatment was to harden and alloy the steel surface which had been previously coated with tungsten carbide (WC) and were introduced using the rotor conveyer to improve the properties of the surface layer. Development of the surface layer was observed in which one can distinguish the remelted zone, heat-affected zone and the transient zone. The fine grained, dendritic structure occurs in the remelted and alloyed zone with the crystallization direction connected with the dynamical heat abstraction from the laser beam influence zone.The fine grained martensite structure is responsible for hardness increase of the alloyed layer. It has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones.The objective of the present work was to study the modification of the microstructure of hot-work tool steels X40CrMoV5-1 and X38CrMoV5-3 during the surface modifying by means of laser technology. The aim of such treatment was to harden and alloy the steel surface which had been previously coated with tungsten carbide (WC) and were introduced using the rotor conveyer to improve the properties of the surface layer. Development of the surface layer was observed in which one can distinguish the remelted zone, heat-affected zone and the transient zone. The fine grained, dendritic structure occurs in the remelted and alloyed zone with the crystallization direction connected with the dynamical heat abstraction from the laser beam influence zone.The fine grained martensite structure is responsible for hardness increase of the alloyed layer. It has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the ...

The paper presents the results of investigations of the 5% cobalt and 2% molybdenum additions in the W-Mo-V and W-V high-speed steels of the 9-2-2, 11-2-2 and 11-0-2 types with economically designed chemical composition on the wear mechanism during cutting and erosion tests. The 5% cobalt addition results in increasing the secondary hardness effect by 1.6 to 1.9 HRC, depending on a steel grade. Secondary hardness effect is caused by the dispersive carbides of the M4C3 type and martensite transformation of the retained austenite. The maximum secondary hardness effect about 66.3-67.6 HRC, depending on a grade of steel, occurs in each steel after tempering at 540oC and austenitizing at 1240oC. The 5% cobalt addition results in enhancing the working properties of tools, longer tool life and makes it possible to increase cutting speed by about 50%, compared with the steels of identical concentration of other alloying elements but without cobalt addition. Cobalt does not have any significant influence on erosion resistance, which is independent of the steel hardness but depends on molybdenum addition in steel.

Presents experimental results obtained with resonant-tunneling diodes fabricated from (GaAl)As/GaAs and (CdMg)Te/CdTe semiconductor heterostructures grown - respectively - by low-pressure metal-organic vapor-phase epitaxy and molecular-beam epitaxy methods. These results demonstrate, firstly, the appearance of intriguing oscillatory structure on the rising slope of the resonant peak in small-diameter (GaAl)As/GaAs-based devices and, secondly, the improvement of current-voltage characteristics of (CdMg)Te/CdTe-based resonant-tunneling diodes due to reduction of their cross-sectional area.

This research project 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 of the performed research structure changes were determined concerning the grain size and reinforcement ceramic particle distribution in the steel surface layer. The reason of this work was to determine the optimal laser treatment parameters, particularly the laser power applied to achieve good layer mechanical properties 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 working conditions. The remelted layers which were formed in the surface of investigated hot work steel were examined metallographically and analysed using light and scanning electron microscope as well as X-Ray diffraction.

The purpose of this paper was characterisation of the structure, mechanical and tribological properties of the monolayers CrN, TiN and multilayers TiN/(Ti,Al)N PVD coatings deposited onto plasma nitrided X37CrMoV5-1 type hot work tool steel. Taking into account the results of measurements, one can state that the lowest wear at certain conditions in both room and elevated temperatures displays the TiN/(Ti,Al)N multilayer coating, what can be connected with their good adherence to the substrate materials as well as the highest hardness. The investigation results will provide useful information to applying the PVD coating for the improvement of wear resistance of tools made from hot work steels. The paper contributes to better understanding of the structure, adhesion and the wear resistance at the elevated temperature up to 500°C of CrN and TiN, TiN/(Ti,Al)N PVD coatings deposition onto hot work tool steel X37CrMoV5-1 type. [Received on 25 October 2005; Accepted on 12 February 2007]

Composite materials reinforced by Nd-Fe-B (hard magnetic material) or FINEMET (soft magnetic material) particles with polymer matrix were manufactured by one-sided uniaxial pressing. The complex relationships among the manufacturing technology of these materials, their microstructure, as well as their mechanical and physical properties were evaluated. The main purpose of obtaining this kind of composite materials is broadening possibilities of nanocrystalline magnetic materials application that influence on the miniaturisation, simplification and lowering the costs of devices. The manufacturing of composite materials greatly expand the applicable possibilities of nanocrystalline powders of magnetically hard and soft materials. However, further examination to obtain improved properties of magnetic composite materials and investigations of constructions of new machines and devices with these materials elements are still needed. This paper shows the base of the technological solution which makes it possible in obtaining magnetic composite materials and mechanical properties of these composite materials. [Received on 15 April 2006; Accepted on 10 February 2007]

The purpose of this paper was characterisation of the structure and properties of functionally gradient hardmetals manufactured by P/M method on the basis of cobalt matrix. The distribution of functionally gradient hardmetals porosity was made using image analysis on the light microscope. Hardness tests of all layers in the sintered test pieces were made with the Vickers method. Density of sintered samples was made using the Archimedes method. In case of the all cemented carbides reinforced with different ceramics particles fabricated, it was found that density of sintered samples depend on reinforced particles. Moreover, density of sintered samples depend on temperatures and atmosphere of sintering process. The investigation results will provide useful information in applying the Powder Metallurgy to manufacturing functionally gradient hardmetals on the basis of cobalt matrix. The project contributes to improving of tool cutting material properties through manufacturing of functionally gradient hardmetals by P/M method. [Received on 15 November 2006; Accepted on 12 February 2007]

This paper presents the application of artificial neural network for the selection of steels' grades with a required hardenability. The purpose has been achieved in two stages. In the first stage, a neural network model for calculating the Jominy curve on the basis of the chemical composition has been worked out. This model made it possible to prepare, in the second stage, a representative set of data and to work out the neural classifier for the selection of steel grade with the required hardenability. The methodology presented in this paper makes it possible to add new grades of steel to the system. The worked out model may be used in computer systems of steel selection for the heat-treated machine parts. [Received 15 April 2006; Accepted 15 March 2007]

Employment of the artificial intelligence tools for development of the methodology of assessing quality and structural defects in Al and Mg alloys and custom-made computer software will make it possible to determine the quality of manufactured element based on digital images registered in the X-ray flaw detection examinations. The possibility to correlate the frequency and morphology of defects with the technological process parameters will make it also possible to identify and classify these defects and control the process to minimise and eliminate them. The methodology is presented in this paper, making it possible to determine the types and classes of defects developed during casting elements from aluminium alloys, making use of photos obtained from the flaw detection method with X-ray radiation. [Received 10 November 2005; Accepted 9 January 2007]