Fouliard Quentin, Haldar Sandip, Ghosh Ranajay, Raghavan Seetha
Appl Opt. 2019 May 1;58(13):D68-D75. doi: 10.1364/AO.58.000D68.
Phosphor thermometry is a promising non-destructive method for accurate temperature measurement using phosphor elements that emit temperature-dependent luminescence. The method relies on the intensity and decay of luminescence arising from the phosphor elements upon excitation by an incident laser. In this work, the classical Kubelka-Munk model has been utilized and modified to model the luminescence emitted from phosphor elements that are added into thermal barrier coatings (TBCs) to enable temperature sensing using phosphor thermometry. The collectible luminescence and its time-decay behavior emerging from a tailorable multilayer TBC configuration have been predicted for different rare-earth dopants: Dy, Er, and Sm within an yttria-stabilized zirconia (YSZ) host, and with an operational gradient of temperature acting through its depth. The configurations have been designed by varying the position and thickness of the doped layer into the coating. The decay constant of the collectible luminescence has been used to determine the position in the coating from where the luminescence decay is the same as the decay of the collectible signal. This subsurface position indicates the location at which the temperature measurement is performed using phosphor thermometry under realistic operating conditions. It has been determined that YSZ:Dy provides the highest intensity of the collectible luminescence among the three dopant materials. In the TBC configuration with a fully doped coating, using YSZ:Er as a sensor enables temperature measurement from a more in-depth position in the coating. It has been shown that this position can be tailored by adjusting the geometrical configuration of the TBCs, varying the position and thickness of the doped layer. Due to the sensitivity of the dopants to temperature, the decay behavior of the emerging luminescence is demonstrated to change for different TBC configurations. The model can be used in screening the dopants to design multilayered TBCs for their suitability in temperature sensing by phosphor thermometry.
磷光测温法是一种很有前景的非破坏性方法，用于使用发射与温度相关发光的磷光体元件进行精确温度测量。该方法依赖于磷光体元件在入射激光激发下产生的发光强度和衰减。在这项工作中，经典的库贝尔卡-蒙克模型已被利用和修改，以模拟添加到热障涂层（TBC）中的磷光体元件发出的发光，从而能够使用磷光测温法进行温度传感。对于不同的稀土掺杂剂：氧化钇稳定氧化锆（YSZ）基质中的Dy、Er和Sm，以及在其深度上起作用的温度操作梯度，预测了从可定制的多层TBC结构中出现的可收集发光及其时间衰减行为。通过改变掺杂层在涂层中的位置和厚度来设计这些结构。可收集发光的衰减常数已被用于确定涂层中发光衰减与可收集信号衰减相同的位置。这个次表面位置表明了在实际操作条件下使用磷光测温法进行温度测量的位置。已经确定，在三种掺杂材料中，YSZ:Dy提供的可收集发光强度最高。在全掺杂涂层的TBC结构中，使用YSZ:Er作为传感器能够从涂层中更深的位置进行温度测量。已经表明，这个位置可以通过调整TBC的几何结构、改变掺杂层的位置和厚度来定制。由于掺杂剂对温度的敏感性，对于不同的TBC结构，出现的发光的衰减行为被证明会发生变化。该模型可用于筛选掺杂剂，以设计多层TBC，使其适用于磷光测温法进行温度传感。
