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Vol. 61, No. 1, May, 2020

CHANGE IN CERAMIC OBJECT SURFACE LAYER STRUCTURE DURING OPERATION. PART 1 V. V. Kuzin,1,2 S. N. Grigor’ev,1 and M. A. Volosova1 Translated from Novye Ogneupory, No. 2, pp. 39 – 45, February, 2020.

Original article submitted January 9, 2020. An original method is used to study the surface layer structure of a VOK-71 ceramic object after diamond grinding. Kinetics of changes in ceramic structure in the contact interaction area during operation are studied. Keywords: ceramic objects (CO), ceramic surface layer (SL), ceramic failure, contact interaction region, ceramic structural elements, stress-strained state, wear site.

Results of research will be published in two parts of the article. In part 1 of the article results are provided for a study of ceramic SL structure after diamond grinding and kinetics for its change in the contact interaction region during operation, and in part 2 outside the region of contact interaction.

INTRODUCTION Under the action of physiochemical factors of a production and operational nature there is change in a ceramic surface layer (SL) structure, its crack growth resistance is reduced, there is an increase in the probability of unpredictable failure, and object reliability is reduced [1 – 3]. Ceramic structure varies both within the contact interaction region with a touching component and also outside this region with direct contactless action of operating loads [4 – 8]. A change in ceramic SL structure in the region of contact interaction during friction is traditionally given fixed attention since in fact this region generates the greatest number of partial and total object breakages [9 – 13]. Reasons for breakage are connected with a change in ceramic SL structure outside the area of contact interaction, studied to a significantly less extent, and existing data point to the considerable complexity and stochastic nature of this process [14]. This does not make it possible to formulate scientifically substantiated requirements for finishing technology for ceramic object manufacture and to predict their operating life precisely. Results of many years of research by the authors of the present article have made it possible to come reliably to a solution of this important task. The stated aim in this work is experimental study of kinetics of the change in SL structure for a ceramic object (CO) in different areas of contact interaction during cutting tests. 1 2

RESEARCH PROCEDURE The requirement of resolving the specific problem needed creation of a procedure capable of revealing and identifying elementary acts in kinetics of the change on CO SL structure. The procedure developed has been created on the basis of CO operating systems [15], which has made it possible to consider the effect of ceramic structure inhomogeneity, stress concentrators, the degree of SL defectiveness, and the specific nature of contact interaction on the kinetics of a change in its structure. Choice of ceramic tool as an object for study gave rise to extreme operating conditions and a sh