Search

The nature of intermetallic NiAl brittleness is investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and electron energy-loss fine structure (EELFS) means. It is found that the reason for this phenomenon is the ordering of intermetallic NiAl, accompanied by the formation of aluminum structural segregations at grain boundaries. Doping with 0.1 wt % La transforms the atomic and electronic structures of grain boundaries, eliminating NiAl intergranular fracturing at room temperature. Doping is accompanied by Fermi level shifts and an increase in conduction electron density neff. These factors are responsible for the lower covalence of interatomic bonds in pure intermetallic NiAl. The effect A1 segregations have on the critical deformation of the generating grain boundary fracture in NiAl is discussed.

We report a comparative study of single-layer (TiAlCrSiY)N and multilayer (TiAl-CrSiY)N/(TiAlCr)N PVD coatings on cutting tools during the break-in stage of high-speed dry cutting. Phase and chemical composition of tribooxides forming in the coating wear area were studied by X-ray photoelectron spectroscopy. It is shown that amorphous oxide films with a thickness of several dozen angstroms contain phases with a chemical composition close to mullite, sapphire, rutile, and chromium oxide. As a result of selective wear, the contact surface of the coatings retains the most durable tribooxides carrying out protective functions. Low-cycle fatigue resistance is studied using the cyclic microindentation technique. Fractal analysis of time-resolved indenter penetration depth curves combined with scanning electron microscopy (SEM) demonstrates phenomenological regularities of coatings’ damageability at the early stage of wear. It is shown that, in comparison with single-layer (TiAlCrSiY)N, the nucleation and growth of microcracks in a multilayer (TiAlCrSiY)N/(TiAlCr)N coating is accompanied by acts of microplastic deformation providing a higher fracture toughness of the (TiAlCrSiY)N/(TiAlCr)N multilayer nanocomposite.

The evolution of the self-organization process where dissipative structures are formed under the extreme frictional conditions associated with high performance dry machining of hardened steels has been studied in detail. The emphasis was on the progressive studies of surface transformations within multilayer and monolayer TiAlCrSiYN-based PVD coatings during the running-in stage of wear when self-organization process occurs. The coating layer was characterized by high resolution electron energy-loss spectroscopy (HREELS). It is shown that the nano-multilayer coating possesses higher non-equilibrium structure in comparison to the monolayer. Comprehensive studies of the tribo-films (dissipative structures) formed on the friction surface were made using a number of advanced surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The data obtained for the tribo-films was combined with the detailed TEM studies of the structural and phase transformations within the underlying coating layer. This data was related to the micro-mechanical characteristics of the coating layer and its wear resistance. It was demonstrated that the evolution of the self-organization process is strongly controlled by the characteristics of the tribo-films formed at different stages of the wear process. Within running-in stage (after length of cut of 15 m) fully protective mullite tribo-films predominantly form on the surface of nano-multilayer coating, establishing a functional hierarchy within the layer of tribo-films. This reduces entropy production during friction and leads to significant surface damage reduction and wear rate stabilization. In contrast, in a monolayer coating with a lower structural complexity, a variety of protective and non-protective tribo-films form during the running-in stage, which cannot fully protect the surface. Therefore the wear rate on the monolayer is not stabilized and its wear resistance is lower. The results obtained show that it is possible to control tribo-films evolution during self-organization by means of increase in structural complexity and the non-equilibrium state of the surface engineered layer with simultaneous tuning of its integrative behaviour.

Lead sulfide (PbS) crystals with sizes from 20 to 500 nm were deposited in chemical bath from an alkaline solution (CBD method). The morphology of specimens was studied using high resolution scanning electron microscopy (HRSEM). Influence of crystallite sizes on the electronic structure was studied with X-ray photoelectron spectroscopy (XPS) and high resolution electrons energy losses spectroscopy (HREELS). The work function was measured with a Kelvin probe microscopy in air.

A multi-functional nano-multilayered Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N physical vapor deposited (PVD) adaptive hard coatings is presented. This novel coating consists of alternating layers with variable chemical composition but similar crystal structure and hardness. A comprehensive investigation of the microstructure and properties of the coating was performed. The structure of the coating before and after service has been characterized by high-resolution transmission electron microscopy (HRTEM). Various micro-mechanical characteristics (hardness, impact fatigue fracture resistance, and low cycling wear resistance) of the coating have been investigated. Oxidation resistance of the coating has been studied using Thermogravimetric–Differential Thermal Analysis (TG-DTA) within a temperature range of 25–1200 °C in air. Wear performance of the novel TiAlCrSiYN/TiAlCrN coating was evaluated through tool life studies, cutting forces measurements and identification of chips characteristics. To determine the causes of improvement in wear performance, the worn surface of the coated cutting tools was investigated using SEM/EDS. The characteristics of the surface tribo-films that were formed on the worn surface were studied using, X-ray photoelectron spectroscopy (XPS) and Extended Energy-loss Fine Spectroscopy (EELFS). One of the major features of this coating is enhanced formation of tribo-oxide films on the surface during friction. These oxides possess a sapphire and mullite structure with superb protective ability that acts simultaneously with high temperature lubricious Si–O and Cr–O phases. Due to emergent properties, the developed adaptive coating behaves as a higher ordered system under operation, capable of sustaining extreme operating conditions.

Machining of hard to cut materials such as hardened steels and high temperature strong aerospace materials is a challenge of modern manufacturing. Two categories of the aluminum-rich TiAlN-based Physical Vapor Deposited (PVD) coatings, namely AlTiN and TiAlCrN, are commonly used for this area of application. A comparative investigation of the structural characteristics, various micro-mechanical properties, oxidation resistance and service properties of the both coatings has been performed. Crystal structure has been studied using High Resolution Transmission Electron Microscopy (HR TEM). Electronic structure has been investigated using X-ray Photoelectron Spectroscopy (XPS). Micro-mechanical properties (microhardness, plasticity index, impact fatigue fracture resistance) have been evaluated using a Micro Materials Nano-Test System. Short-term oxidation resistance has been studied at 900 °C in air. The tool life of the coating was studied during ball nose end milling of hardened H 13 tool steel as well as end milling of aerospace alloys such as Ni-based superalloy (Waspalloy) and Ti alloy (TiAl6V4). It was shown that the set of characteristics that control wear performance strongly depend on specific applications. For machining of hardened tool steels, when heavy loads/high temperatures control wear behavior, the coating has to possess a well-known combination of high hot hardness and improved oxidation resistance at elevated temperatures. To achieve these properties, crystal structure for TiAlN-based coatings should be mainly B1, and elemental composition of the coating should ensure formation of strong inter-atomic bonds such as Al–Cr metal-covalent bonds in the TiAlCrN coating. Nano-crystalline structure with grain size of around 10–30 nm enhances necessary properties of the coating. In contrast, for machining of aerospace alloys, when elevated load/temperature combined with intensive adhesive interaction with workpiece material results in unstable attrition wear with deep surface damage, the coating should possess a different set of characteristics. Crystal structure for TiAlN-based coatings is basically B1; but due to a high amount of aluminum, the AlTiN coating contains AlN domains. The coating has a very fine-grained nano-crystalline structure (grains sized around 5 nm). Electron structure of energy levels indicates formation of metallic bonds. This results in plasticity increase at the cost of hot hardness reduction. The surface is able to dissipate energy by means of plastic deformation (instead of crack formation) and in this way, surface damage is reduced.

The microstructure and electronic structure of nanodispersed (Al 67 Ti 33 N) and (Ti 10 Al 70 Cr 20 N) PVD coatings were investigated by high-resolution transmission electron microscopy (HRTEM) and electron spectroscopy techniques: X-ray photoelectron spectroscopy (XPS) and high-resolution electron energy loss spectroscopy (HREELS). The grain size measured by HRTEM was 5–20 nm for Al 67 Ti 33 N and TiAlCrN type coatings, correspondingly. The spinodal decomposition of Al supersaturated nitrides under its deposition was found. Chromium increases the metastable solubility of h -AlN in c -Ti 1 − x Al x N. The lifetime of the cutting tools with Al-rich coatings has been evaluated under ball nose end milling of hardened tool steel H13 (HRC 50–52) and aerospace materials. TiAlCrN coatings are preferable for steel machining, and AlTiN coatings are better for aerospace material processing. It was found that AlTiN coating has lower hardness but higher plasticity and improved impact fatigue fracture resistance. The TiAlCrN coating has much better hot hardness and oxidation stability at high temperatures, but it is stiffer than AlTiN.

In this study the cemented carbide cutting tools with a nano-crystalline Al0.67Ti0.33N hard PVD coating deposited by cathodic arc evaporation were annealed within a range of temperatures 700–800 °C during 2 h in vacuum. The changes in structure and properties of the coating vs. temperature have been analyzed using TEM as well as high temperature nano-indentation methods. Cutting tools with the annealed AlTiN coating have been run through a number of cutting tests with varying conditions. The conditions were as following: 1) continuous cutting: turning of annealed 1040 steel (HB 220); 2) interrupted cutting: turning of 4340 steel (HRC 40); 3) end milling: ball nose end milling of hardened H13 steel (HRC 50). The cutting tool life has been investigated before and after annealing of the Al0.67Ti0.33N coatings at different temperatures. The relations between high temperature hardness and plasticity of the Al0.67Ti0.33N coating and tool life under varying cutting conditions was outlined.

Application of quaternary nitride nano-multilayered coatings results in significant improvements in tool life as well as wear behavior of ball nose end mills under severe conditions of dry high speed machining of hardened H13 steel (HRC 55–57). Tool life of different nano-multilayered TiAlCrN-based coatings with addition of transitional metals based (of V and VI groups) nitride layers has been compared. Tool life of TiAlCrN/NbN coating was found to be higher than compared to the other nano-multilayered coatings. Investigation of surface structure characteristics of the TiAlCrN/NbN coating using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and High Resolution Electron Energy Loss Spectroscopy (HREELS) has been performed. The properties of the coatings such as microhardness, modulus of elasticity, coefficient of friction and oxidation stability at elevated temperatures were also studied. Cutting forces at the tool/workpiece interface have been measured in-situ. Temperatures on the surface of cutting tools were evaluated. The features of friction and wear behavior as well as mechanisms of tribo-adaptation of TiAlCrN/NbN nano-multilayered coatings were outlined.

In this study, cemented carbide inserts with nano-crystalline Al0.67Ti0.33N coating deposited by cathodic arc evaporation, were annealed in vacuum at temperatures 700 and 900 °C during a time period of 2 h and ran through a turning test. The micro-structural characteristics, a number of micro-mechanical properties (microhardness, elastic modulus, elastic recovery parameter, microhardness dissipation parameter, critical load values during scratch testing, low cycling wear resistance) measured at room and elevated temperatures (up to 600 °C) as well as cutting tool life and wear behavior have been investigated before and after annealing using optical metallography, SEM, XRD, XPS, and HREELS methods. The results indicate the impact of microstructure formed during annealing on the mechanical and tribological properties as well as wear behavior of cutting tools with a Al0.67Ti0.33N coating.

Application of quaternary nitride (Ti,Cr,Al) N/WN nano-multilayered coatings results in a significant increase of tool life as well as wear behavior improvement under conditions of dry high-speed machining (end milling) of hardened H13 steel (HRC 50). Investigations of surface structure characteristics of TiAlCrN/WN coatings using TEM, SEM, EDX, and XPS have been performed. The microhardness, modulus of elasticity, coefficient of friction and the oxidation stability of the coatings were also studied. Cutting forces at the tool/workpiece interface have been measured in situ. It was shown that the major cause of the cutting tool life and wear behavior improvement is the enhanced tribological adaptability of a TiAlCrN/WN coating. By means of adding W to the composition of TiAlCrN/WN nano-multilayered coatings, W–O tribo-films form in synergy to alumina and provide tool life improvement.

New accurate data of the neutron-proton spin-dependent total-cross-section difference ΔσL(np) at the neutron-beam kinetic energies 1.39, 1.69, 1.89, and 1.99 GeV are presented. In general, these data complete the measurements of energy dependence of ΔσL(np) over the Dubna Synchrophasotron energy region. Measurements were carried out at the Synchrophasotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research. The quasi-monochromatic neutron beam was produced by breakup of extracted polarized deuterons. The deuteron (and hence neutron) polarization direction was flipped every accelerator burst. The initial transverse (with respect to beam momentum) neutron polarization was changed to a longitudinal one and longitudinally polarized neutrons were transmitted through the large proton longitudinally polarized target. The target polarization direction was inverted after one to two days of measurements. Four different combinations of the beam and target parallel and antiparallel polarization directions, both oriented along the neutron-beam momentum, were used at each energy. A fast decrease in −ΔσL(np) with increasing energy above 1.1 GeV and a structure in the energy dependence around 1.8 GeV, first observed from our previous data, seem to be well revealed. The new results are also compared with model predictions and with phase-shift analysis fits. The ΔσL quantities for isosinglet state I = 0, deduced from the measured ΔσL(np) values and known ΔσL(pp) data, are also given. The results of the measurements of unpolarized total cross sections σ0tot(np) at 1.3, 1.4, and 1.5 GeV and σ0tot(nC) at 1.4 and 1.5 GeV are presented as well. These data were obtained using the same apparatus and high-intensity unpolarized deuteron beams extracted either from the Synchrophasotron or from the Nuclotron.

The application of ternary nitride (Ti,Cr,Al)N coatings with high aluminum content deposited by a new plasma enhanced cathode method results in a significant cutting tool life improvement. To investigate this improvement the tool life of end milling cutting tools was studied under severe conditions associated with the high speed dry machining of H13 steel (hardness HRC 50). Investigations of the surface structure characteristics for the different compositions of TiAlCrN as well as TiAlN coatings using SEM, EDS, AES, and XPS were performed. The coefficient of friction and oxidation stability of the coatings were also measured at elevated temperatures. It was shown that the major cause of the improved cutting tool life is the adaptability of the (Ti0.10Cr0.20Al0.70)N coating under conditions experienced during high performance machining. The tribological adaptability manifests itself through the formation of complex alumina/chromia-like tribo-films on the surface of the cutting tool. This tribo-film formation serves to protect the surface of the tool and improve its lubricity during cutting. Due to the presence of these beneficial films the tendency of the workpiece material to adhere to the tool within the cutting zone is also reduced. The shape and microstructure of the chips formed during end milling were also analyzed. Both of these characteristics indicate significantly improved lubrication properties at the cutting tool/workpiece interface when the TiAlCrN coating is applied.

New accurate results of the neutron-proton spin-dependent total cross section difference $\Delta\sigma_{\mathrm L}(np)$ at the neutron beam kinetic energies 1.39, 1.69, 1.89 and 1.99 GeV are presented. Measurements were carried out in 2001 at the Synchrophasotron of the Veksler and Baldin Laboratory of High Energies of the Joint Institute for Nuclear Research. A quasi-monochromatic neutron beam was produced by break-up of extracted polarized deuterons. The deuteron (and hence neutron) polarization direction was flipped every accelerator burst. The vertical neutron polarization direction was rotated onto the neutron beam direction and longitudinally (L) polarized neutrons were transmitted through a large proton L-polarized target. The target polarization vector was inverted after 1-2 days of measurements. The data were recorded for four different combinations of the beam and target parallel and antiparallel polarization directions at each energy. A fast decrease of $\Delta\sigma_{\mathrm L}(np)$ with increasing energy above 1.1 GeV was confirmed. The structure in the $\Delta\sigma_{\mathrm L}(np)$ energy dependence around 1.8 GeV, first observed from our previous data, seems to be well pronounced. The new results are also compared with model predictions and with phase shift analysis fits. The $\Delta\sigma_{\mathrm L}$ quantities for isosinglet state I = 0, deduced from the measured $\Delta\sigma_{\mathrm L}(np)$ values and the known $\Delta\sigma_{\mathrm L}(pp)$ data, are also given. The results were completed by the measurements of unpolarized total cross sections $\sigma_{0\mathrm{tot}}(np)$ at 1.3, 1.4 and 1.5 GeV and $\sigma_{0\mathrm{tot}}(n$ C) at 1.4 and 1.5 GeV. These data were obtained using the same apparatus and high intensity unpolarized deuteron beams were extracted either from the Synchrophasotron, or from the Nuclotron.

The main advantage of the filtered arc deposition (FAD) technique is a significant grain refinement that leads to the formation of nano-crystalline (grain size approx. 60–80 nm) PVD coatings. This technique improves the wear resistance of FAD TiAlN coatings under high-speed machining conditions when cutting tool oxidation wear is dominant. A study of the surface structure characteristics of the FAD TiAlN coatings using SEM, EDS, TEM, AES, SIMS and EELFS was performed. The microhardness of the coatings were measured. The microstructure of the chips was analyzed. The compression of the chips as well as shear angle was measured. The friction parameter on the rake surface of the tools was determined in-situ. It was shown that the major cause of the high wear resistance of the FAD coatings during high-speed machining was the formation of the thin protective oxide films on the cutting tool surface. The grain size refinement of the coating promotes the formation of protective alumina films. These films are formed at the surface of nano-crystalline FAD TiAlN coating during high-speed machining. They mainly consist of protective alumina, whereas the films that are forming on the surface of TiAlN commercial coatings with coarser grains consist only of non-protective titania. The formation of the protective alumina films, composed of complicated amorphous–crystalline structures, significantly improves the friction and wear performance of coated tools. The tendency of the work piece material to adhere is reduced and considerably more heat is dissipated via chip removal. This is a major cause of the enhanced wear resistance of the FAD coating technique. Tribo-oxidation during cutting is a typical process of the self-organization of TiAlN coatings that results in a quasi-stabilization of cutting tool wear. The self-organization and friction control for coated cutting tools is considered based on a non-equilibrium thermodynamic approach.

The possibility of production of alloyed NiAl intermetallic compound having satisfactory processing ductility at room temperature has been investigated. The samples were made by extrusion of sintered powder blanks. The effect of Fe, Cr, Co, Mo, B and La doping on mechanical properties of nickel aluminide was investigated. Alloying has a beneficial effect on decrease of the ductile–brittle transition temperature and micro-mechanism of fracture. The doping of nickel aluminide by Fe (2 at.%), Mo (2 at.%) and Co(2 at.%) was studied by valence band XPS and plasmon losses electron spectroscopy. The shift of the Fermi level (EF) and variation of density of conduction electrons −neff were found in doped NiAl. The results show good correlation between EFneff and micro-hardness of alloyed NiAl intermetallic.

Preliminary results of the ΔσL(np) at 1.4, 1.7, 1.9 and 2.0 GeV are presented. They were obtained during the two data-taking runs at the JINR Dubna Synchrophasotron in 2001 and complete the existing data above 1.1 GeV. The data analysis is in progress. The aim of the present studies is to determine the imaginary and real parts of the np spin-dependent forward scattering amplitudes over this energy range.

The paper considers some ways to improve surface engineered coatings for cutting tools. These coatings were formed by two stages: diffusion saturation with nitrogen (ion nitriding) and application of the (Ti, Cr)N hard coating by means of the cathode arc plasma deposition process (CAPDP). The coating includes also an additional ion alloyed layer applied to the previously nitrided surface of HSS. Such multilayered coating makes it possible to significantly increase (in 2.1–2.4 times) the wear resistance of a cutting tool by extending the stage of normal wear. There were studied 16 chemical elements implanted into the base surface and those of four antifrictional materials effecting on the life of a HSS cutter with a surface engineered coating. It was shown that leading positions in wear resistance are taken by coatings with a modified sublayer of elements with high antifrictional properties. A compromise between the high wear resistance and reliability of a coating, which is characterized by a high adhesion to the substrate, is observed in the multilayered coating that contains a sublayer enriched with indium. Indium is present in the sublayer both in metal and bound states (In–N). The positive effect of indium on wear resistance appears to be tied with two types of phenomena developing on the friction surface. Acting as a liquid lubricant, indium in metal state leads to reducing the friction coefficient. At the same time, when heated at cutting, indium is partly oxidized with developing of oxygen-containing phases protecting the surface when passing from the normal stage of tool wear to the avalanche-like one. This is beneficial for prolongation the stage of normal friction, considerably enhancing the tool life.

New data on the spin-dependent np observables measured with quasi-monochromatic polarized neutron beam in the energy region from 1.2 to 3.7 GeV are presented. Further measurements of np scattering observables using the JINR LHE polarization facility (longitudinal and transverse polarized neutron beams and a polarized proton target) are discussed. The aim of these studies is to determine the imaginary and real parts of the forward scattering amplitudes for np and for isospin I=0 systems above 1.1 GeV.

New results of the neutron-proton spin-dependent total cross section difference $\Delta\sigma_L(np)$ at the neutron beam kinetic energies 1.59, 1.79 and 2.20 GeV are presented. Measurements were performed at the Synchrophasotron of the Laboratory of High Energies of the Joint Institute for Nuclear Research in Dubna. A quasi-monochromatic neutron beam was produced by break-up of extracted polarized deuterons. Neutrons were transmitted through a large polarized proton target. Measurements were performed either with a parallel or an antiparallel beam and target polarizations, both oriented along the beam momentum. The results at the two higher energies were measured with two opposite beam and target polarization directions. Only one target polarization direction was available at 1.59 GeV. The present measurements agree well with existing data. A fast decrease of the $-\Delta\sigma_L(np)$ values with increasing energy above 1.1 GeV was confirmed. The new results are also compared with model predictions and with phase shift analysis fits. The $\Delta\sigma_L$ quantities for isosinglet state I=0, deduced from the measured $\Delta\sigma_L(np)$ values and known $\Delta\sigma_L(pp)$ data, are given.

The behaviour of fine-mesh vacuum phototriodes (VPTs) with the external diameters of 21 and 25 mm has been investigated in an axial magnetic field up to 4 T in view of their applications as readout devices for CMS Endcap Electromagnetic Calorimeter. The measured VPT parameters are: the photocathode's sensitivity and its homogeneity, the gain in zero and 4 T magnetic field at tilt angles corresponding to the pseudorapidity range of CMS ECAL Endcap 1.48–3.0 as a function of fine-mesh cell dimensions, excess noise factor and the stability of the photocathode response under the illumination by light emission diodes (LED) and the irradiation by 14 MeV neutrons. Phototriodes with 100 lines per mm fine-mesh and 25 mm external diameter are found to be the best candidates for coupling with rear PbWO4 crystals by dimensions of 30×30 mm, proposed to be used in CMS ECAL Endcaps. VPTs provide a gain of the order (6–8) in a 4 T magnetic field and an excess noise factor of 2–2.5 under illumination of a full photocathode's area.

Experience with polarized targets and achieving of very low temperatures gave rise to the idea of using a new technique based on dissolving 3He in 4He to create a frozen spin polarized target. The short history of the development of such proton and deuteron targets at the Laboratory of Nuclear Problems (LNP) JINR is given. Recently, the Saclay-Argonne frozen spin proton polarized target used initially in E704 experiment at FERMILAB was upgraded with adding the missing parts and the first physics experiments was carried out. At present, a new project is being proposed. The aim of this project is the development of effective methods of production 6LiD irradiated material for a large volume polarized deuteron target with a high polarization. The research will be carried out with use of the microtron of Czech Technical University for irradiation and the existing polarized target at Charles University Nuclear Centre for tests of the target materials.

Some approaches to friction control by alloying of new generation powder tool materials (high-speed steel (HSS) based deformed compound powder materials or DCPMs) are suggested. The first way implies reduction of self-organization level thanks to a decrease of friction coefficient at the operating temperatures. The second is realized by the addition of 5% Al 2 O 3 . On the basis of modern tribology conclusions the extension of the interval of self-organization by means of stable high-strength secondary structure developing on the tool surface is advanced as the second principal of alloying. This is implemented by employing a 2% BN (hexagonal) addition. Application of both approaches makes it possible to expect a significant total increase of tool life. This is realized by using a 20% TiCN addition.

Characteristic features of wear in tools made of high-speed steel (HSS) based deformed compound powder materials (DCPMs) were investigated at cutting. It was shown that HSS-based powder tool materials additionally alloyed by titanium carbides feature an abnormally high wear resistance and could be placed into a new class of self-organizing tool materials. In particular, DCPM-containing titanium carbide as a base and HSS as a binder can be classed with such materials. Self-organization of such materials is manifested in their ability to form stable high-strength phases that effectively protect the surface from external impacts at cutting. It was found using AES and SIMS methods, that during the process of cutting one can observe the transformation of carbide TiC into thin surface films in the form of titanium-oxygen compounds. This substantially enhanced frictional properties at operational temperatures and significantly increased the cutting tool wear resistance. As a result, the wear resistance of this tool is 2.0–3.5 times higher than that of usual high-speed steel tools.

Adaptive TiAlCrSiYN-based coatings show promise under the extreme tribological conditions of dry ultra-high-speed (500-700 m min-1) machining of hardened tool steels. During high speed machining, protective sapphire and mullite-like tribo-films form on the surface of TiAlCrSiYN-based coatings resulting in beneficial heat-redistribution in the cutting zone. XRD and HRTEM data show that the tribo-films act as a thermal barrier creating a strong thermal gradient. The data are consistent with the temperature decreasing from approximately 1100-1200 degrees C at the outer surface to approximately 600 degrees C at the tribo-film/coating interface. The mechanical properties of the multilayer TiAICrSiYN/TiA1CrN coating were measured by high temperature nanoindentation. It retains relatively high hardness (21 GPa) at 600 degrees C. The nanomechanical properties of the underlying coating layer provide a stable low wear environment for the tribo-films to form and regenerate so it can sustain high temperatures under operation (600 degrees C). This combination of characteristics explains the high wear resistance of the multilayer TiAlCrSiYN/TiAICrN coating under extreme operating conditions. TiAlCrSiYN and TiAlCrN monolayer coatings have a less effective combination of adaptability and mechanical characteristics and therefore lower tool life. The microstructural reasons for different optimum hardness and plasticity between monolayer and multilayer coatings are discussed.

Characteristic features of wear in tools made of high-speed steels with surface engineered coatings incorporating ion nitriding and (Ti, Cr) nitride CAPDP (cathode arc plasma deposition process) coatings were investigated at increased cutting speeds in the vicinity of 50–100 m min−1. The wear kinetics, the change of micro-relief of cutter surface and the depth of the unhardened zone of cutting indexable inserts made of high-speed steels with surface engineered coatings were studied. A significant tool life was found for the surface engineered high-speed steel under the greatest possible localization of thermomechanical effects in the CAPDP coating layer. The application of a surface engineered system composed of a heat resistant high-speed steel T15 (P12M3φ2K5) substrate, with surface modified by ion nitriding and then by CAPDP (Ti, Cr) N coating, provides this result.

Changes in chemical composition and fine (at atomic level) structure characteristics of surfaces during the life time of cutting tools were investigated by using AES, SIMS and EELFAS methods. High-speed steels M2 and T15 with coatings incorporating ion nitriding and (Ti, Cr) nitride CAPDP (cathode arc plasma deposition process) were used. It was found that, under the wear conditions studied (such as cutting of medium carbon steels), some components of the protective hard coating dissociated, forming quasi-oxide amorphous films. This shows the parallel developing processes of: 1. Dissociation of chemical compound in coating material (Ti, Cr) N and intensive diffusion (absorption) of nitrogen into chip. 2. Creation on tool surface of stable amorphous protecting quasi-oxide TiO films. The discovered changes in chemical and phase composition of contact surfaces of the “tool-workpiece” tribopair improve service characteristics of the cutting tool and promote its adaptation to service conditions (named “self-organization”). The adaptation observed is expressed more on steel T15 with high heat resistance and leads to a significant increase of tool life.

Results of the total cross section differenceΔσL in anp transmission experiment at 1.19, 2.49 and 3.65 GeV incident neutron beam kinetic energies are presented. Measurements were performed at the Synchrophasotron of the Laboratory of High Energies of the Joint Institute for Nuclear Research in Dubna. Results were obtained with a polarized beam of free quasi-monochromatic neutrons passing through the new Dubna frozen spin proton target. The beam and target polarizations were oriented longitudinally. The present results were obtained at the highest energies of free polarized neutrons that can be reached at present. They extend the energy range of existing results from PSI, LAMPF and Saclay measured between 0.066 and 1.10 GeV. The new results are compared withΔσL(pn) data determined as a difference betweenΔσL(pd) andΔσL(pp) ANL-ZGS measurements. The values ofΔσL for the isospin stateI=0 were deduced using knownpp data.

We have measured the analyzing power for elastic scattering of {pi}{sup +} from a target of polarized {sup 1}H. Data were taken for incident pion beam energies of 165 and 240 MeV at several pion scattering angles. The current data generally agree with previously existing measurements of {ital A}{sub {ital y}} for this reaction and also with results of the SAID phase-shift analysis program. In most cases the new data are of higher precision than previously existing data. {copyright} {ital 1996 The American Physical Society.}

Blanking dies constitute heavily loaded tribosystems with low-cycle friction fatigue being the primary mechanism of their wear. In this paper the authors consider characteristic features of steels with 12% chromium content which are widely used in the manufacture of blanking dies. It has been found that in the course of die operation certain secondary protective structures are formed on its surface, significantly influencing the wear process. Structural changes in subsurface layers as well as the role of these changes in blanking die friction have been studied. Principles of friction control have been advanced for the tribosystems under analysis.

The inclusive vector analyzing power [ital iT][sub 11] of [pi][sup +][r arrow][sup 7]Li elastic scattering and inelastic scattering to the 0.47 MeV excited state was measured at several angles for [ital T][sub [pi]]=134, 164, and 194 MeV. The polarization effects were found to be small but nonzero, the trend of the data is well described by a coupled channels calculation. The results of the calculation are more sensitive to variations of the nuclear structure input than to variations of the reaction mechanism.

The vector analyzing power [ital iT][sub 11] of the reaction [pi][ital d][r arrow][ital pp] was measured at [ital T][sub [pi]]=350, 400, and 450 MeV. The results obtained at [ital T][sub [pi]]=350 MeV are in agreement with earlier measurements of [ital iT][sub 11] at 325 MeV. With increasing energies our results show a marked increase in the vector analyzing power up to a value close to its theoretical limit at [ital T][sub [pi]]=450 MeV ([radical][ital s] =2.40 GeV). In this energy region broad structure has been found in earlier measurements of [ital d][sigma]/[ital d][Omega] and [ital A][sub [ital y]0].

Self-organization during friction in complex surface engineered tribosystems is investigated. The probability of self-organization in these complex tribosystems is studied on the basis of the theoretical concepts of irreversible thermodynamics. It is shown that a higher number of interrelated processes within the system result in an increased probability of self-organization. The results of this thermodynamic model are confirmed by the investigation of the wear performance of a novel Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N (PVD) coating with complex nano-multilayered structure under extreme tribological conditions of dry high-speed end milling of hardened H13 tool steel.

Polyphenylene binders based on acetyl aromatics with hydroxyphenyl bridges and acetophenone and composite materials were subjected to infrared radiation. The thermomechanical properties were investigated.

The asymmetry parameter P was measured for the elastic pion-proton scattering in the very backward angular region of theta_cm ~ 150-170^o at several pion beam energies in the invariant mass range containing most of the pion-proton resonances. The general goal of the experimental program was to provide new data for partial wave analyses in order to resolve their uncertainties in the baryon resonance region to allow the unambiguous baryon spectrum reconstructions. Until recently the parameter P was not measured in the examined domain that might be explained by the extremely low cross section. At the same time the predictions of various partial wave analyses are far from agreement in some kinematic areas and specifically those areas were chosen for the measurements where the disagreement is most pronouncing. The experiment was performed at the ITEP U-10 proton synchrotron, Moscow, by the ITEP-PNPI collaboration in the latest 5 years., Comment: 6 pages, 5 figures. to be submitted to the European Physical Journal

Oligophenylenes containing various amounts of acenaphthenyl groups are synthesized by copolycyclocondensation of ethyl ketals of 4,4′-diacetyldiphenyl oxide, 5-acetylacenaphthene, and acetophenone. Treatment of these with 2,3-dichloro-5,6-dicyance 1,4-benzoquinone (DDQ) under conditions obtaining in model reactions for the dehydrogenation of acenephthene to acenaphthylene and transformation of 1,3,5-tris-(5′-acenaphthenyl)benzene into 1,3,5,-tris-(5′-acenaphylenyl)benzene results in the formation of oligophenylenes containing acenaphthylenyl groups (OAL), some of these groups apparently existing in the form of π-complexes with DDQ. Some thermal characteristics of OAL samples structurized at 200–300°C are indicated.

Polycyclocondensation of acetylacenaphthalene and 4,4′-diacetyldiphenyl oxide or their ethyl ketals has been used to synthesize acenaphthene-containing oligopheyylenes and the possibility of obtaining from them acenaphthylene-containing oligophenylenes in a quite simple way has been explored. It is shown that treatment of the acenaphthene-containing oligophenylene with p -chloranil results in the formation of oligophenylenes containing π-complexes of acenaphthene fragments with p -chloranil. The spatial structuring of such oligophenylenes at 200–250°C is carried out through the reactions of the fragments indicated. Some properties of the three-dimensional polymers thereby formed are investigated.

The ITEP-PNPI collaboration presents new results of the measurements of the spin rotation parameter A in the elastic scattering of negative pions on protons at P_beam=1.43 GeV/c. The results are compared to the predictions of several partial wave analyses. The experiment was performed at the ITEP proton synchrotron, Moscow., 4 pages, 5 figures

The ITEP-PNPI collaboration presents the results of the measurements of the spin rotation parameter A in the elastic scattering of positive and negative pions on protons at P_beam = 1.62 GeV/c. The setup included a longitudinally-polarized proton target with superconductive magnet, multiwire spark chambers and a carbon polarimeter with thick filter. Results are compared to the predictions of partial wave analyses. The experiment was performed at the ITEP proton synchrotron, Moscow., 7 pages, 3 figures. To be published in Phys. Lett. B