TiCxNy and TiCx-TiN films obtained by CVD in an ultrasonic field

TiC _x N _y mono- and TiC_x-TiN double-layer films with a thickness of 30 to 100 m were prepared on a carbon steel (C: 0.6 to 0.7%) substrate by CVD in an ultrasonic field (ultrasound frequency: 19kHz; power: 10 to 20Wcm^–2). The moderate deposition conditions for obtaining an adherent and thick film of TiC _x N _y were: substrate temperature: 1050° C; H₂, N₂, TiCl₄ and CH₄ flow rates: 6.2, 4.0, 0.9 and 0.26 to 2.0 ml sec^–1, respectively. The growth rate, grain size and degree of 2 2 0 preferred orientation were found to decrease with increase in CH₄ concentration. TiC _x N _y film on carbon steel had a Vickers microhardness of 1800 to 2600 and an adhesion strength to the substrate of more than 120 kg cm^–2. A TiC _x -TiN (x0.5) double-layer film was obtained at 1050° C by a controlled alternative deposition of TiC _x or TiN. Quasiepitaxial growth of crystallites in the double layers was found to prevail in both coatings of TiC _x (220)/TiN (220)/steel and TiN (200)/TiC_x (200)/steel.     

Change in temperature field distribution during electric-arc hardening

The distribution of temperature fields during electric-arc hardening is investigated. A model of the temperature distribution with respect to a hardened zone depth is developed for different carbon-content steels subjected to electric arc hardening. The calculated results are compared with experimental data to show good agreement.Ural Polytechnic Institute, Ekaterinburg. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 2, pp. 172–176 August, 1992.     

Transient-temperature and residual-stress fields in axisymmetric metal components after hardening

Abstract

A finite-element method is used to analyse the transient–temperature and residual-stress fields in an axisymmetric metal specimen during quenching. In the calculation of transient-temperature fields it is assumed that an unsteady source of latent heat exists in the specimen when a phase transformation occurs. Factors such as the surface heat transfer coefficient, heat conductivity coefficient, linear expansion coefficient, density, specific heat capacity, latent heat, and so forth are all temperature dependent. The elastic-plastic properties of the specimen are modified according to temperature fields, which are determined; the influence of plastic deformation on the temperature fields is neglected. The agreement between the calculated results and the experimental data shows that the numerical analysis method is reliable. The method may also be applied to the analysis of specimens with other than axisymmetric shape.

MST/15     

Analytical study of heat and mass transfer in the hardening kinetics of concrete heat-treated in an electromagnetic field

The results are given from an analytical and experimental study of the kinetics of the heat treatment of ferroconcrete slab structures in an alternating electromagnetic field.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 2, pp. 286–292, February, 1970.     

Influence of an electric field on the hardening process and the properties of an epoxy composite discretely reinforced with phosphocarbon fibers

The influence of an electric field on the hardening process, the structure, and the properties of an epoxy composite in the presence of a phosphorus-containing carbon filler has been investigated. It has been shown that under the action of an electric field the process of formation of a three-dimensional epoxy polymer in the presence in the system of phosphocarbon fibers proceeds more intensively with the formation of a more rigidly bound structure of the polymer as compared to the same composition hardened in the absence of the field. It has been established that the fibrous filler-binder interface has a dominant role in the formation of a spatially cross-linked polymer and in the properties of the product hardened both under the action of the electric field and without it. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 3, pp. 47–54, May–June, 2007.     

Fiber characterization in a stationary ultrasonic field

An instrument has been developed to characterize the mean dimensions of softwood fiber samples. It is based on the phenomenon that particles of cylindrical shape diluted in water and shorter than one fourth of the acoustic wavelength migrate to nodal planes of acoustic radiation pressure and reorient parallel to these planes when subjected to a stationary ultrasonic field. As the resonator operating frequency is 72 kHz, fibers up to 5 mm in length can be measured. The time evolution of the fiber suspension during ultrasonic excitation is monitored with a collimated beam of light. Scattered light signals collected off-axis in the plane perpendicular to the acoustic nodal planes are shown to be a function of the weighted average fiber length. Results are presented for pulp samples in the average fiber length range of 0.2 to 3 mm. It was found that there is a region where the scattered light is linearly related to concentration. Acoustooptical measurements obtained at initial concentration in this linear region, for all fractions, have shown that the longer the average length from screen classifier is, the faster the layer formation is. Since the fiber length the radius are proportional for a wood species, this observation is in agreement with the theoretical prediction.     

Calculating the radiative exchange of heat in media consisting of nonisothermal components

We have analyzed the combustion of a coarsely dispersed fuel under low-temperature conditions to ascertain the influence exerted on the radiative exchange of heat by nonignited fuel particles. The calculations are compared against experimental results.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 56, No. 4, pp. 581–586, April, 1989.