Thermodynamic Model of the Metallic Friction Process

An energy model of stabilized friction and wear is presented. Heating of a definite mass of surface material to the flash point, in consideration of the mass’s specific heat and wear, is assumed to provide the basis for thermal processes. An energy balance is presented in the form of a first law of thermodynamics formula for open systems. Two new magnitudes, referred to as complex systemic constants C and D, are developed and their physical meaning is interpreted. These complex systemic constants are subsequently employed to describe the tribological system. Among other magnitudes in the model, density of thermal dissipation and enthalpy flux, power density of mechanical dissipation, wear severity, and specific work of wear are described. Friction and wear testing results [Ciecieląg, 1994, “Energy Conditions of Metal Resistance to Tribological Wear,” Ph.D. thesis, Świętokrzyska Technical University, Kielce; Żurowski, 1996, “Energy Aspect of Increasing Wear-Resistance of Metals in the Process of Engineering Dry Friction,” Ph.D. thesis, Świętokrzyska Technical University, Kielce; Sadowski and Żurowski, 1992, “Thermodynamic Aspects of Metals' Wear-Resistance,” Tribology and Lubrication Engineering, 3, pp. 152–159] are employed to describe, in quantitative terms, selected tribological systems on the basis of the presented thermodynamic model. A method of determining the complex systemic constants C and D is developed. Specific work of wear, wear severity, probability of emergence of a flux of tribological wear products, and relation of worn mass to heated mass and flash temperature as functions of temperature are defined. This paper concludes with application, significance, and advantages of the complex systemic constants C and D, and phenomena arising in frictional contact between two metals.