| Design and experimental results are presented for an apparatus which uses ultraviolet Raman spectroscopy to measure local temperature, pressure and chemical information in situ at a ball bearing/sapphire plate interface, also known as a ball-on-flat, while controlling temperature, loading, contact mode, and contact speed. The final design of the apparatus provided a functional instrument, albeit without all the features originally envisioned. The area interrogated by the UV laser beam was on the order of the size of the contact between the ball and plate. Studies of the degradation of hexadecane at the contact point under friction conditions over time at varying temperatures provide support for the formation of polyaromatic hydrocarbons (PAHs) and aliphatic ethers at very low temperatures (20°C). It is believed that this work is the first time the formation of PAHs at such low temperatures in a tribometer has been observed. |
