Surface Hardening of Steels and Alloys Using a Corona Discharge

Metal Science and Heat Treatment -     

Investigation of accuracy characteristics of the method of interchannel gradient reconstruction of digital color images

Results of computational experiments aimed at studying the accuracy characteristics of interchannel gradient reconstruction of signals of color digital images distorted by impulse noise with different brightness distribution laws, which are not correlated between the channels, are generalized. Examples of interchannel reconstruction of color digital images on the basis of different sets of gradient estimates are presented.     

Structural transformations and distribution of elements in steels during high-speed carbonitriding

Conclusion Induction heating of components at a high rate and feeding to the heating zone a dosed portion of active liquid provides preparation on them of diffusion layers with a controlled, sufficiently high content of carbon and nitrogen corresponding to that recommended. No redistribution of chromium and nickel in steel 40KhN was detected.The best results are obtained after high-temperature impregnation of components, interrupted cooling to the austenite decomposition temperature by a pearlitic mechanism, and repeated hardening.Physicotechnical Institute, Academy of Sciences of the Belorussian SSR, Minsk Automobile Factory, Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. I, pp. 33–36, January, 1987.     

Structural transformations taking place in the surface layers of very fine BaFe12O19 powder particles

Conclusions During the comminution of powders of the ferrite BaFe₁₂O₁₉ in an attritor mechanical energy is expended in the disintegration of particles, formation of defects, and plastic deformation of the crystal lattice. The comminution of powders in a vibratory mill is accompanied by the formation of well-developed surface layers on particles, which are characterized by a high degree of defectiveness and crystal lattice disorder. The hypothesis is advanced that during prolonged comminution of powders in a vibratory mill the surface layers of particles can undergo structural transformations, which promote the formation of stable oxygen-containing phases at crystallite boundaries.Translated from Poroshkovaya Metallurgiya, No. 6(258), pp. 50–55, June, 1984.     

A Correct Diagnosis of a Pseudopatient in an Inpatient Setting.

Rosenhan (1973) reported his data on eight pseudopatients who deliberately feigned auditory hallucinations and subsequently gained admission to 12 psychiatric institutions. From this data he concluded that "sanity" and "insanity" were indistinguishable in the context of a psychiatric hospital. The case study presented here is significant because it fails to conform to the experience of Rosenhan. A pseudopatient was presented for interview at a weekly diagnostic conference in an inpatient setting. He was felt to be "normal" by the interviewer, residents, and other staff at the conference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of electron-beam melting and heat treatment on the structure,composition, and properties of tool steels

A method was developed for the surface-melting and quench-hardening of tool steels through the use of electron-beam heating. The distribution of alloying elements in characteristic treatment zones was studied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 1, pp. 121–129, January, 1988.     

Promising methods of surface hardening for titanium alloys and steels with rapid heating

Conclusion Surface electron-beam heat treatment of steels leads to formation of hardened layers 1–5 mm thick having a finely acicular martensitic structure with increased hardness. There is redistribution of alloying elements, acceleration of decomposition processes during heating of hardened specimens, and compressive stresses arise. Heating in a flashing schedule for steels reduces the overall area of inclusions up to a factor of 6.6, and combined with subsequent heat treatment it excludes nonuniform distribution of alloying elements.Use of electrodeposited coatings during electrochemical heat treatment sharply intensifies reaction diffusion processes. During siliciding of titanium alloys with a copper underlayer the thickness of diffusion layers reaches 975 m, and during carburizing of titanium with an iron coating it reaches 1050 m. In this way there is a sharp increase in titanium alloy wear resistance.With rapid heat treatment of alloys with electrodeposited and gas heat-treatment coatings there is rebuilding of the surface structure with formation of fine blocks 0.5–10 m in size, twins, and slip bands. The size and structure of the transitional diffusion zone depends on the presence of a metal underlayer, and treatment schedule. As a result of electron-beam surface treatment the adhesive strength is improved (up to _ad= 200–210 N/mm²) and the wear resistance of gas heat treatment coatings (by a factor of two to three). The friction coefficient for electrodeposited chromium coatings increases by a factor of 1.5–2 with an increase in loads by a factor of two to three.Physicotechnical Institute, Academy of Sciences of the Belorussian SSR. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 45–49, October, 1987.     

Change in the crystal structure and strength of sendust alloy under the effect of a corona discharge

The effect of treatment in a corona discharge on the crystal structure and strength of Sendust alloy is described. The methods of x-ray diffraction analysis and nuclear gamma resonance spectrometry are used to show that treatment in a corona discharge causes redistribution of atoms and vacancies between the surface layer and the volume part of the crystallite and between its sublattices. It is shown that by treating the alloy in a corona discharge, its strength characteristics and electromagnetic parameters can be improved and the load causing the appearance of cracks can be increased considerably. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 18–22, December, 1999.