Process for the production of an optically selective coating of a substrate for high temperature receiver solar devices and relative material obtained
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Solution Overview
Problem
Current selective coatings for solar receiver devices in concentrated solar thermal plants face challenges in maintaining high solar absorbance while minimizing thermal emissivity, especially at high temperatures, leading to inefficiencies in energy conversion and increased heat losses.
Innovation Solution
A process for producing an optically selective coating on receiver substrates using a multilayer structure comprising a high-melting metal (W) layer, a metal-ceramic composite (CERMET) layer with YPSZ as the ceramic matrix, and an antireflection layer, deposited using DC/RF sputtering without the need for matching layers, optimizing the coating's optical and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the operating temperature of the receiver device is increased to improve energy conversion efficiency, then the thermal energy output increases, but the thermal emissivity losses increase and the coating's mechanical and chemical resistance deteriorates
Solution Approach 1:
The coating is divided into multiple functional layers: a bottom reflective layer (W, Mo, or Ta) for thermal radiation management, intermediate CERMET layers (metal particles in ceramic matrix) for optical absorption enhancement, and top protective layers for chemical and mechanical resistance. Each layer segment performs a specific function to collectively resolve the temperature-related contradictions.
Solution Approach 2:
The patent employs composite CERMET structures combining metals (high solar absorbance) with ceramics (thermal stability and low emissivity). This composite approach allows simultaneous achievement of high energy conversion efficiency and reduced thermal losses by leveraging the complementary properties of constituent materials.
2Reliability
If a multilayer coating structure is implemented to achieve high solar absorbance and low thermal emissivity, then the optical efficiency improves, but the manufacturing complexity and process steps increase
Solution Approach 1:
The patent optimizes specific parameters of each layer (thickness, composition ratios, deposition conditions) to achieve the desired optical properties. By carefully controlling these parameters, high optical efficiency is obtained while managing the complexity of the multilayer structure through systematic parameter optimization rather than arbitrary design.
3Ease of manufacture
If conventional coating materials are used to maintain simplicity in coating formulation, then the ease of manufacture is improved, but the coating's resistance to high temperature thermal, chemical and mechanical stress deteriorates
Solution Approach 1:
Different regions of the coating have specialized properties tailored to their specific functions: the bottom layer uses high-melting-point metals for thermal stability, intermediate layers use CERMET composites for optical performance, and surface layers use chemically resistant ceramics for protection. This local differentiation of material quality achieves high temperature resistance while maintaining reasonable manufacturing feasibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The coating achieves high absorptance (α=0.893) with low emissivity (ε=0.087 at 550°C), enhancing energy conversion efficiency by minimizing heat losses and maintaining mechanical integrity, thus improving the overall performance of solar thermal plants.
Implementation Method 1
deposition of a layer reflecting infrared radiation consisting of a high-melting metal, preferably W, on said heated receiver substrate; deposition on the high-melting metal of one or more layers of metal-ceramic composite materials (CERMET)
Implementation Method 2
deposition of a layer reflecting infrared radiation consisting of a high-melting metal, preferably W, on said heated receiver substrate; annealing under the same temperature and pressure conditions as the deposition of the reflecting layer
Data Source
AI summary
A process for the production of an optically selective coating of a receiver substrate of a suitable material for solar receiver devices particularly suitable for operating at high temperatures, more specifically for receiver tubes of linear parabolic trough, which comprises: deposition of a layer reflecting infrared radiation consisting of a high-melting metal on a heated receiver substrate of a suitable material; annealing under the same temperature and pressure conditions as the deposition of the reflecting layer; deposition on the high-melting metal of one or more layers of metal-ceramic composite materials (CERMET), wherein the metal is W and the ceramic matrix is YPSZ (“Yttria-Partially Stabilized Zirconia”); deposition on the cermet of an antireflection layer; annealing under the same temperature and pressure conditions as the depositions of the cermet and antireflection layers.