Abstract— This paper presents a method for determining the friction coefficients of an antifriction coating based on silver with the addition of molybdenum disulfide or graphite in vacuum. The method for determining the coefficients of friction is implemented at a vacuum tribometer. The dependences of the friction coefficients in the contacting pair consisting of steel ShKh-15 and an antifriction coating based on silver with the addition of molybdenum disulfide and, in another case, graphite, were obtained depending on the ambient pressure. The values of the average friction coefficient in a pair of a ball made of ShKh-15 steel and a ring with an antifriction coating containing 94% silver and 6% molybdenum disulfide were obtained to be 0.114 with a standard deviation of 0.012 and 0.168 with a standard deviation of 0.01 at an atmospheric pressure of 1000 and 0.03 mbar, respectively. For the antifriction material based on silver with the addition of 6% graphite, the friction coefficient varies from 0.144 to 0.26 as the pressure changes from 1000 up to 0.03 mbar. Analytical dependences of the friction coefficient for both antifriction materials on the height of ascent in the atmosphere have been obtained, which will make it possible to develop the procedure for calculating spherical articulated bearings for high-altitude aircraft.