Metal-ceramic Material Research Articles

Effect of Sintering Aids Sorts on Properties of Prepared Al<sub>2</sub>O<sub>3</sub>-Al Cermet

Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, Al-Al2O3 cermet is prepared adding different sintering aids via the powder metallurgy method to study the properties of Al-Al2O3 cermet. The conclusions are shown the adding sintering aids can significantly improve the sintered density of Al-Al2O3 cermet. The sintering aiding effect of adding MgO is better than that of SiO2 and Y2O3, and the hardness and the strength of the sample are higher than those of samples with SiO2 and Y2O3, and the densification degree of Al-Al2O3 metal ceramic material is the best, the relative density is 94.8%, the surface hardness is 824HV. The flatness of the surface of the sample adding MgO shows that the bonding strength between aluminum powder and alumina powder is high. The prepared Al-Al2O3 cermet adding different sintering aids have higher density and fewer pores in the microstructure the prepared Al-Al2O3 cermet adding sintering aids has a package structure.

Synthesis of Porous Composite Materials via Combustion of a Mixture of Titanium, VT6 Alloy, and Amorphous Boron Powders

Self-propagating high-temperature synthesis without preheating has been realized in powder mixtures consisting of large spherical VT6 titanium alloy granules, small dendritic titanium particles, and black amorphous boron. Synthesis in a combustion wave involved a few steps: first, boron reacted with fine-particle titanium to form a boride matrix, which then reacted with molten VT6 titanium alloy granules. We have obtained a porous metal–ceramic material similar in structure to composites.

Development and Investigation of a Two-Layer Metal—Ceramic Material for Protective Barriers in Conditions of High-Speed Impact

The possibility of improving the physico-mechanical characteristics of composite materials used in protective structures against a high-speed impact is considered. By means of self-propagating high-temperature synthesis, a two-layer cermet is obtained: the front layer is a cermet based on titanium diboride with a titanium nickelide bond, and the back layer is a titanium alloy. The study by the computational-experimental method of the impact resistance of this composite in comparison with a homogeneous titanium plate showed a qualitative advantage expressed in the absence of a shock crater in a cermet plate after a collision with a steel spherical impactor and stronger deformation and prefracture of the impactor. The two-layer cermet has a high resistance to the penetration of the steel impactor.

Synthesis of Two-Layer Metal–Ceramic Materials with High-Velocity-Impact Resistance Based on Refractory Compounds and Titanium

We consider the possibility of obtaining composites with increased mechanical strength resistant to high-velocity impact by means of self-propagating high-temperature synthesis (SHS) of metal–ceramic materials with graded composition–in particular, of layered type. A two-layer combined metal–ceramic material has been developed comprising NiTi-bonded titanium diboride (TiB2) layer on a metallic titanium substrate layer. The impact resistance of this composite is advantageous to that of a homogeneous titanium plate, which is manifested by the absence of a spall crater upon the impact of a spherical steel projectile and by stronger deformation and prefracture cracking of the projectile.

Синтез двухслойного металлокерамического материала на основе тугоплавких соединений и титана для условий высокоскоростного соударния

AbstractWe consider the possibility of obtaining composites with increased mechanical strength resistant to high-velocity impact by means of self-propagating high-temperature synthesis (SHS) of metal–ceramic materials with graded composition–in particular, of layered type. A two-layer combined metal–ceramic material has been developed comprising NiTi-bonded titanium diboride (TiB_2) layer on a metallic titanium substrate layer. The impact resistance of this composite is advantageous to that of a homogeneous titanium plate, which is manifested by the absence of a spall crater upon the impact of a spherical steel projectile and by stronger deformation and prefracture cracking of the projectile.

Multiobjective optimization of ceramic-metal functionally graded plates using a higher order model

A methodology of multiobjective design optimization of ceramic–metal composite plates with functionally graded materials, with properties varying through the thickness direction, obtained by an adequate variation of volume fractions of the constituent materials, is presented in this paper. Constrained optimization is conducted for different behavior objectives like the maximization of buckling load or fundamental natural frequency. Mass minimization and material cost minimization are also considered. The optimization problems are constrained by stress based failure criteria and other structural response constraints or manufacturing limitations. The design variables are the index of the power-law distribution in the metal-ceramic graded material and the thicknesses of the graded material and/or the metal and ceramic faces.An equivalent single layer finite element plate model having a displacement field based on a higher order shear deformation theory, accounting for the temperature dependency of the material properties, was developed and validated for the analysis of through-the-thickness ceramic-metal functionally graded plates. The optimization problems are solved with two direct search derivative-free algorithms: GLODS (Global and Local Optimization using Direct Search) and DMS (Direct MultiSearch). DMS, the multiobjective optimization solver, is started from a set of local minimizers which are initially determined by the global optimizer algorithm GLODS for each one of the objective functions.

Preparation of Coated Type Al-Al<sub>2</sub>O<sub>3</sub> Cermet Composite Powders via the Calcination Oxidation Method

Cermet while maintaining the excellent properties of ceramic materials, but also have the advantages of a metal material, is an important new engineering materials. In this paper, prepared by calcination of alumina - aluminum metal-ceramic composite material powder, and its characterization as a basis to provide raw materials for preparing high performance metal ceramic material. According to the research, with the calcination temperature is increased, the rate of change gradually increase the weight of aluminum. Calcined at a temperature of 600¡æ, the oxidation of aluminum surface the best. With the firing time increases, the rate of change in the weight of aluminum powder showed an increasing trend. When 8h, oxidation of aluminum surface better. Through this experiment, process optimization can be found in the calcination temperature was 600¡æ, calcination time is 8h, the best coating effect aluminum surface, coating evenly, clean interface, the reaction layer thickness of about 700nm, the prepared package type composite powders the best results.

Wear of friction pairs made of titanium carbide-based metal–ceramic material

The wear of direct and reverse friction pairs made of TiC–ZhS6U titanium carbide-based metal–ceramic material and the metal component of this material, i.e., the ZhS6U nickel-base casting superalloy, has been studied. Both uncoated friction pairs and pairs with TiN and TiC coatings have been tested under a load of 2 N at a velocity of sliding of 0.15 m/s. It has been found that TiC–ZhS6U + TiC–TiC–ZhS6U + TiC has the highest wear resistance.

The Research Status of the Wetting of Metal/Ceramic in the High Temperature Self-Lubricating Materials

The wettability of solid lubricant and matrix sintered body is very important for the production of the high temperature self-lubricating composite material. The wettability of the metal/ceramic is ubiquitous phenomenon in materials science and people have long the research in this field. Research on the wettability of the ceramic/metal has important practical significance for developing new type of metal/ceramic systems, exporing and developing the preparation technology of material, and preparing high performance of metal/ceramic composite materials. In this paper, from the wetting phenomenon of the metal/ceramic, the commonly used theory of the wettability research is stated, various experimental methods of wettability are introduced, and the significant importance of improving the wettability for developing metal ceramic friction material is indicated. What’s more, some methods of improving the wettability are proposed.

Some aspects of dynamic coupled response of functionally graded thin-walled columns with square cross-sections under in-plane pulse compression

The present paper deals with a dynamic coupled response of functionally graded columns with a quadratic cross-section subjected to an in-plane pulse loading. An Al-TiC metal-ceramic material is applied. It is assumed that functionally graded materials (FGMs) are subject to Hooke’s law. The thin-walled structures are simply supported at the ends. This study is devoted to the stability problem of rectangular dynamic pulse load. The effects of temperature, wave propagation and damping are neglected. In order to obtain the equations of motion of individual plates, the classic laminate plate theory (CLPT) has been modified in such a way that it additionally accounts for all components of inertial forces. A plate model is adopted for the structures. The problem of an interaction of the global mode with the local ones is concerned (i.e., a three-modes approach). Attention has been focused on some unexpected aspects related to dynamic interactive buckling of columns having two axes of the cross-section symmetry. In the present study, a new approach to the description of this phenomenon, based on Koiter’s theory, has been applied.

Static interactive buckling of functionally graded columns with closed cross-sections subjected to axial compression

The present paper deals with static coupled buckling of thin-walled columns with trapezoidal and square cross-sections, which are made of functionally graded materials (FGMs). An Al–TiC, metal-ceramic material is applied. The discussion assumed that the columns were axial compressed and simple supported at their ends. In addition, the material is subject to Hooke’s law. The effect of temperature is neglected. The classical laminate plate theory (CLPT) has been used to describe properties of the functionally graded structures. The problem of the non-linear buckling was solved by using a variational method for the asymptotic analytical–numerical method (Koiter’s theory). Static interaction of the global buckling mode with the two local buckling modes has been taken into account. In order to derive the equilibrium equations of functionally graded structures, the full Green’s strain tensor and the second Piola–Kirchhoff’s stress tensor has been adapted. The presented problem is particularly important as the authors have found no earlier studies on coupled buckling of thin-walled functionally graded structures with closed cross-sections.

High Temperature Cylinder Sleeve Design Research Self-Lubricating Materials

Cylinder Liner design innovation goal is energy conservation. As the main friction parts engine cylinder liner, reducing friction energy is energy saving basic requirements. Materials research cylinder sleeve is one of the main cylinder liner saving research. Through the piston ring and cylinder liner surface friction dual material hard phase, self-lubricating phase, toughening phase analysis, select compatibility, high strength, heat resistance, good high temperature performance, ease of manufacture, price rational matrix material and an appropriate proportion of nanoscale hard material, self-lubricating materials, ductile materials, using appropriate methods cladding and processing, design developed high-temperature self-lubricating cylinder sets of advanced materials. The latest international high temperature, wear-resistant, self-lubricating materials research: modern nanoα-Al2O3+Ni-base alloy composite materials, Ti2B/Fe metal-ceramic composites, metals and ceramics NiCr-Cr3C2 particles CaF2 self-lubricating composite alloy powder material, NiCr/Cr3C2-WS2 self-lubricating wear-resistant materials were studied and found to TiC, Al2O3 is hard reinforcing phase, CaF self-lubricating phase, NiCr/TiC eutectic toughening phase, high-temperature self-lubricating wear-resistant nanocomposite, and Cr18Ni9 class alloy as base material, by laser cladding method enables conventional cylinder liners manufacturing technological breakthroughs, has practical value.

Studying microprofile of surface of steel disc that operates in various friction units in a pair with MK-5 metal-ceramic frictional material

Results of studying the roughness of the working surface of a steel disk that operates in a pair with a copper-based metal-ceramic frictional layer under film lubrication are presented. The dependence of the root-mean-square roughness on the duration of operation in the steady wear mode is obtained. The microstructure of the 65G steel is identified at various values of the hardness and the dependence of the ultimate strength on the hardness is obtained. Recommendations on selecting rough surfaces and mechanical characteristics of the 65G steel for operation in a pair with the MK-5 metal-ceramic material are given.

Study of tribological behavior of metal-ceramic friction material MK-5 obtained by freely spread layer technique for hydromechanic transmissions

The tribological behavior of a metal-ceramic friction material for hydromechanical transmissions of heavy-duty transport vehicles is studied. It is shown that the average wear of the driven plates after the tests simulating mean loading conditions of clutches is 0.025 mm (with permissible 0.06 mm) and the wear of drive plates is 0.0247 mm (with permissible 0.05 mm). The tests of a retarder brake show that the wear of the drive and driven plates does not exceed the required values. The friction plates manufactured by the Molodechno Plant of Powder Metallurgy are tested under operating conditions of BelAZ dump trucks. The alteration of the method for producing the MK-5 friction material, and thereby its hardness, does not have an effect on the wear rate.

Bending Analysis of Functionally Graded Sandwich Plates Under the Effect of Mechanical and Thermal Loads

The bending response of sandwich plates subjected to thermo-mechanical loads is studied. The sandwich plate faces are assumed to have isotropic, two-constituent (metal-ceramic) material distribution through the thickness, and the modulus of elasticity, Poisson's ratio, and thermal expansion coefficient of the faces are assumed to vary according to a power law distribution in terms of the volume fractions of the constituents. The core layer is still homogeneous and made of an isotropic ceramic material. Several kinds of sandwich plates are used, taking into account the symmetry of the plate and the thickness of each layer. Field equations for functionally graded sandwich plates whose deformations are governed by either the shear deformation theories or the classical theory are derived. Displacement functions that identically satisfy boundary conditions are used to reduce the governing equations to a set of coupled ordinary differential equations with variable coefficients. Exact solutions for functionally graded materials (FGMs) sandwich plates are presented. Numerical results of the sinusoidal, third-order, first-order, and classical theories are presented to show the effect of material distribution on the deflections and stresses. A wide variety of results is presented for the static response of sandwich plates under thermo-mechanical loads. The effects of thermo-mechanical loads and other parameters on the dimensionless deflections and axial and transverse shear stresses of an FGM sandwich plate are studied.

Temperature and thermal stresses in material of a pad during braking

The transient temperature field and corresponding quasi-static thermal stresses are analysed in a system consisting of a semi-space and a strip. The strip is heated on its outer surface by a heat flux with the intensity equal to the specific power of friction during braking with a uniform retardation. The evolution and distribution in depth from a surface of friction for temperatures and thermal stresses were investigated for the metal-ceramic FMK-11 material of the strip.

Transient and thermal contact analysis for the elastic behavior of functionally graded brake disks due to mechanical and thermal loads

In this paper, the transient and contact analysis of functionally graded (FG) brake disk is presented. The analysis was carried out using ANSYS parametric design language (APDL). The FG brake disk is made of metal–ceramic material. The material properties vary in radial direction with the values from full-metal at the inner radius to that of full-ceramic at the outer radius. In the analysis, FG brake disk is in contact with one pure pad disk and coulomb contact friction is considered as heat source. The non-dimensional results are obtained for specific value of grading index ( n = 1) by considering different material property divisions of 25, 50, 100 and 200. The results presented are for the pressure distribution, total stress, pad penetration, friction stress, heat flux and temperature during contact, for different values of contact stiffness factor, F kn , which depends on the property gradation of FG brake disk with 200 material property divisions. The results show that the contact pressure and contact total stress increase with increasing values of F kn , and hence it can be concluded that gradation of the metal–ceramic has significant effect in the thermomechanical response of FG brake disks.

Experience with use of S-1-U synthetic antifriction metal-ceramic material in thrust bearings of hydraulic generators

1. The use of S-1-U antifriction material, instead of B83 babbitt, for coating metal pads improves substantially the reliability of the thrust bearings of hydraulic generators, while maintaining a high (over 90 kg/cm2) mean specific pressure in order to reduce the friction losses, the overall dimensions, and the quantity of metal in the thrust bearings. 2. The physicochemical, antifriction, and breaking-in properties of the S-1-U material permit improving the constructional and erection-operation parameters of thrust bearings and make it possible: a) to reduce the torque by a factor of about 4 and thus to facilitate the starting conditions as well as the rotation of the rotor in the shutdown unit; b) to eliminate the scraping of the pad bearing surfaces during erection and maintenance; c) to allow the temperature of the oil in the bearing bath to increase to 65°C; d) to start the units under low oil temperatures (5°C), and also after extended shutdowns without raising the rotor on the brakes; e) to avoid the use of a special installation for supplying oil under pressure to the friction surfaces, taking into account the fact that such an installation complicates the construction and operation of the thrust bearings. 3. Prospects have been opened for the manufacture of thrust bearings intended to operate under large axial loads (to 5000 tons).