Effect of Flash Temperature on Tribological Properties of Bulk Metallic Glasses

Abstract

The tribological properties of Cu-based and Zr-based bulk metallic glasses (BMGs) sliding against Si 3 N 4 under dry and water lubrication were studied on a pin-on-disc tribometer. The wear mechanisms of bulk metallic glasses were investigated based on the calculated flash temperature. The friction coefficients if fully amorphous alloy are about 0.7, while those of BMGs with nanocrytalline are a little higher. The wear rates of Cu-based BMG (V101) are about one order of magnitude lower than those of Zr-based BMG (Vit1) under dry friction, even two orders of magnitude lower under water lubrication. The wear resistance of bulk metallic glasses was influenced by the flash temperature. The calculated flash temperature (3,337 K) on the friction surface of Zr-based amorphous alloy exceeds its glass transition temperature, even its melting temperature. The high flash temperature leads to glass transition accompanied with viscous flow and material transfer, which is responsible for the poor wear resistance of Zr-based BMGs.

Tuning apparent friction coefficient by controlled patterning bulk metallic glasses surfaces

“…It is generally accepted that most of frictional work during the wear process is converted into heat, which in turn, raises the interface temperature, modifies properties of sliding surfaces such as forming oxide layer or even melting interfacial materials31323334. Here, The maximum contact temperature rise Δ T max can be estimated by the following equation35,…”

Thermal Conductivity and Wear Behavior of HVOF-Sprayed Fe-Based Amorphous Coatings

“…Correspondingly, the wear was also reduced, resulting in the lowest wear rate, as shown in Figure 9. In addition, due to the hardness of high carbon martensitic GCr15 steel decreased at this temperature (about 633 HV [19]), intensifies the wear of GCr15, leading to the highest wear rate compared to that at room temperature and 200 • C. Notably, as sliding at 400 • C, the actual contact temperature of friction surface during sliding process might be elevated and possibly higher than glass transition (T g ) and crystallization temperature(T x ) [35][36][37]. Hence, it is possible a subsequent crystallization took place.…”

Effects of environment on the sliding tribological behaviors of Zr-based bulk metallic glass

“…It can be calculated that v w is 625. T * c is the actual equivalent temperature, T * c ¼ aH=K c , substituting H with H 0 , K c is the equivalent thermal conductivity, which is less than K m , and can be substituted with 0.8K m [29]. Thus, T * c is 2913 K. N is the total number of asperities, N ¼ ðr 0 =r a Þ 2 F w ð1 À F w Þ þ 1, r 0 is the radius of the pin, r a is the radius of contact units.…”