Effects of aluminizing treatments on high-temperature corrosion of MoSi2-based alloys

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Project title

Code/計畫編號

NSC101-2221-E019-031-MY2

Translated Name/計畫中文名

鋁化改質效應對MoSi2基合金抗高溫腐蝕之研究

Project Coordinator/計畫主持人

Wu Kai

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Optoelectronics and Materials Technology

Website

https://www.grb.gov.tw/search/planDetail?id=2860091

Year

2013

Start date/計畫起

01-08-2013

Expected Completion/計畫迄

31-07-2014

Bugetid/研究經費

1062千元

ResearchField/研究領域

材料科技

「鋁化改質效應對MoSi2基合金高溫腐蝕特性研究」本計畫探討「鋁化改質效應對MoSi2基合金抗高溫腐蝕之研究」，茲將兩年內的研究要點分述如下: A. 第一年度 (1) 本研究擬將探討添加不同鋁含量(1~15at%)及表面滲鋁處理對MoSi2合金在700℃~1200℃間之恆溫氧化影響(三種不同氧分壓)，及評估不同鋁含量對提升合金整體抗氧化性能的效應。 (2) 所有製備的三元合金之恆溫氧化是在熱重分析儀(TGA)中進行，藉由高靈敏之TGA以連續監測氧化後的質量變化量來探討不同Al含量之三元合金的氧化動力學行為，並瞭解其氧化反應機制；另外，評估表面滲鋁改質處理對提升MoSi2合金之抗氧化特性，並藉由田口式分析法，找出最佳的滲鋁參數(包含滲鋁溫度、時間、不同活化劑及成份比例) ，並透過TGA量測確定其抗氧化性能之提升效果。 (3) 所有氧化實驗後之試片將分別利用X-光繞射分析儀及金相顯微分析來探討氧化物組織及成份分布情形，並配合電子探測儀、歐傑電子能譜儀、掃描及穿透電子顯微鏡來分析氧化物形貌與腐蝕物空間分布之差異。預期透過本計畫之研究成果，能完整有系統地建立鋁化改質處理對MoSi2合金抗高溫氧化之資料庫，並將研究成果發表於國際期刊。 B. 第二年度 (1) 針對第一年度研發之最佳三元(MoSi2+X％Al)合金及最佳表面滲鋁條件之改質後合金進行高溫循環氧化及熱腐蝕研究，以探討含鋁化改質後的MoSi2基合金是否能兼具抗氧化及熱腐蝕的特性。 (2) 原則上循環氧化之高、低溫循環時間以4小時為一循環(約含升、降溫1小時，及恆溫2小時) ，並視情況進行重複多次循環氧化之測試(皆在TGA內進行)；另一方面熱腐蝕將以披覆NaCl，Na2SO4及50%NaCl/50% Na2SO4之腐蝕源為主，探討上述合金在700~850℃之熱腐蝕行為(將在直立式石英加熱爐中進行)，以瞭解其反應機制與循環及恆溫氧化之差異性。 (3) 循環氧化及熱腐蝕後的試片分析與第一年度相似；預期經過兩年有系統地研究後，本計劃能將研究成果發表於國際期刊，同時也有系統建立含鋁之MoSi2基合金抗高溫氧化及熱腐蝕之資料庫，供產學業界應用。 Effects of aluminizing treatments on high-temperature corrosion of MoSi2-based alloys A two-year research proposal of 「Effects of aluminizing treatments on high-temperature corrosion of MoSi2-based alloys」 is proposed. The main goals of this research proposal can be described yearly as follows: A. In the first year: (1) The effects of various Al contents and surface aluminizing (pack concentration of Al) on the isothermal oxidation of MoSi2-based alloys are studied over the temperature range of 700 ~1200oC in three various partial pressures of oxygen in order to study the role of Al on the enhanced oxidation resistance of the alloys. (2) All the oxidation tests will be performed by continuously measuring mass-change data through thermal gravimetric analysis (TGA). The oxidation-kinetics behavior and oxidation mechanism of both MoSi2-xAl ternary alloys and MoSi2-based alloys with surface aluminizing treatments will be discussed systematically. In addition, the optimal surface-aluminizing parameters (based on Taguchi-experimental analyses), containing aluminizing temperature, exposure time, various activators, and composition of modification materials will be studied. The evaluation of surface aluminizing treatments on the oxidation-resistant performance will also be investigated after TGA measurements. (3) The scale constitution and phase composition of the alloys will be initially investigated by X-ray diffractory (XRD) and optical microscopy. The detail scale constitution and spatial distribution of the scales will be further explored through SEM, EPMA, Auger and TEM analyses. The primary goal of the first-year study is to systematically enhance oxidation resistance of MoSi2-based alloys and to publish the results in SCI-based journals. B. In the second year: (1) According to the results of the first year, the cycling oxidation and hot corrosion of the optimal MoSi2-based alloys (containing the ternary Al addition and aluminizing process) will be further investigated. The results will compare to those obtained in the first year in order to fully understand the best-performance corrosion resistance of MoSi2-based alloys. (2) In general, the cyclic duration of time for each high-to-room temperature cycle is set for around 4 hours, containing 1-hr heating, 2-hr isothermal exposure, and 1-hr cooling. Each cyclic oxidation test may continuously run up to several cycles (in TGA furnace) depending on temperature and alloy composition. On the other hand, the hot corrosion of the same alloys deposited with various NaCl, Na2SO4, or mixed salts will also be studied in a tube furnace over the temperature range of 700-850oC. The discrepancy of the results obtained between the first- and second-year will be systemically addressed. (3) The microstructure analyses and characterization will be similar to those used in the first year. The final goal of this research proposal is to not only publish all the individual results on international journals, but wholly establish the data base of the high-temperature corrosion of MoSi2-based alloys, which can be applied for industrial applications and manufacturing processes.

Keyword(s)

鋁化改質
MoSi2合金
高溫腐蝕
腐蝕動力學
反應機制
Aluminizing treatment
MoSi2-based alloy
high temperature corrosion
corrosion kinetics
reaction mechanism

DSpace CRIS

Effects of aluminizing treatments on high-temperature corrosion of MoSi2-based alloys

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