Experimental investigation of thermal contact conductance at low temperature based on fractal description

An experimental investigation of thermal contact conductance was conducted with pressed pairs of aluminum alloy 5052 and stainless steel 304 over the low temperature range from 155 to 210 K, with nominal contact pressure from 1 to 7 MPa. The contact surfaces were prepared through bead blasting and characterized with the fractal dimension D and the parameter G of the Weierstrass-Mandelbrot function. The range of fractal dimension is 1.59-1.86 for aluminum and 1.56-1.92 for stainless steel. And the parameter G is in the magnitude of 10−7 m. From the measured results, thermal contact conductance over this temperature range (155-210 K) is less than that near or above room temperature (T > 300 K). The load sensitivity at low temperature is less than that at room temperature. The smaller fractal dimension D characterizes the rougher surface when G is on the same magnitude and results in the smaller value of the contact conductance and insensitivity to the contact pressure.