Work

Utilizing Fly Ash from Coal-Fired Power Plants to Join ZrO2 and Crofer by Reactive Air Brazing

Year: 2025

Type: article

Abstract: This study attempts to use fly ash as the brazing filler additive to increase the sustainable use of coal-fired power plant by-product materials. The experimental results show that adding 5 wt% fly ash into the Ag paste filler contributes to the interfacial reactions in heterogeneous reactive air brazing (RAB) of the ZrO2 and Crofer alloy. The Ag-rich phase dominates the brazed zone. The interfacial reaction layers contain oxidation of the Cu-Ti coating layer, Crofer alloy, and the Si/Al-rich oxides from the fly ash particles. The 5% fly ash RAB joint maintained airtightness for 280 h under 2 psig helium at room temperature. When the test temperature was raised to 600 °C for 24 h, the pressure of the joint assembly still did not drop. When the fly ash addition was increased to 10 wt%, the joint assembly was no longer leak-free at room temperature. Many visible voids and cracks exist in the brazed zone and at the ZrO2/braze and braze/Crofer interfaces. A high volume fraction of the fly ash particles results in many brittle Si/Al-rich oxides in the joint after RAB, and the fracture of these oxides significantly deteriorates the airtightness of the joint. This study shows the feasibility and potential of introducing 5 wt% fly ash particles to the Ag-rich paste filler during the RAB of ZrO2 and Crofer for airtight applications.

Source: Materials

DOI: 10.3390/ma18091956

Authors: Shu-Wei Chang, Ren-Kae Shiue, Liang-Wei Huang

Institutions: National Taiwan University, Taiwan Power (Taiwan), National Atomic Research Institute

Language: English

Topic: Advanced Welding Techniques Analysis

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Responsible consumption and production, Affordable and clean energy, Industry, innovation and infrastructure

Open Access status: gold

Estimated APC paid: $3,137