We present a new technique designed for in situ measurement of pressure and temperature in lubricating films. An innovative methodology has been developed, based on the photoluminescence properties of non-intrusive CdSe-based nanosize sensors (quantum dots). The sensitivity to pressure and temperature of these sensors dispersed in a carrier fluid was established through calibrations performed in diamond anvil cells. Elastohydrodynamic (EHD) contacts of different combinations of contacting solids (glass-steel, glass-Si₃N₄, sapphire-steel and sapphire-Si₃N₄) and submitted to various operating conditions were studied through in situ experiments and numerical simulations. Isothermal experiments were performed first: both experimental central pressures and pressure profiles were obtained, with a very good agreement with the values predicted by the numerical model. A series of non-isothermal experiments were then carried out to perform temperature measurements. Temperature rises in the central zone of EHD contacts involving various material pairs were measured and compared to predictions, leading to a very satisfying agreement. Overall, the deviation between measurements and predictions remained smaller than the uncertainty of the measurement method. Therefore, these findings proved the potential of the methodology to probe in situ pressure and temperature in EHD contacts. Comparative performance with competing techniques was examined in terms of intrusiveness, level of reliability, spatial resolution, accuracy and complexity. As this work is a pioneering development, the technique may be improved in the near future, opening an avenue for even more accurate or faster measurements for example, and eventually offering a better understanding of the mechanisms at work in this type of lubricated interface.

中文翻译：

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基于CdSe的量子点作为弹性流体动力接触中的原位压力和温度非侵入式传感器

我们提出了一种新技术，旨在原位测量润滑膜中的压力和温度。基于非侵入式基于CdSe的纳米尺寸传感器（量子点）的光致发光特性，已经开发了一种创新的方法。这些分散在载液中的传感器对压力和温度的敏感性是通过在金刚石砧座中执行的校准来确定的。接触固体（玻璃钢，玻璃Si ₃ N ₄，蓝宝石钢和蓝宝石Si ₃ N ₄）的不同组合的弹性流体力学（EHD）触头）并通过各种原位实验和数值模拟研究了各种操作条件。首先进行等温实验：获得了实验中心压力和压力曲线，与数值模型预测的值非常吻合。然后进行了一系列非等温实验以进行温度测量。测量了涉及各种材料对的EHD触点中心区域的温升，并将其与预测值进行了比较，从而得出了非常令人满意的协议。总体而言，测量和预测之间的偏差仍然小于测量方法的不确定性。因此，这些发现证明了该方法在探测EHD触点中的原位压力和温度方面的潜力。在侵入性，可靠性水平，空间分辨率，准确性和复杂性方面检查了与竞争技术的比较性能。由于这项工作是一项开创性的发展，因此该技术可能会在不久的将来得到改进，例如为更准确或更快速的测量提供了一条途径，并最终使人们更好地了解了这种润滑界面中的工作机理。