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標題: | 磁控濺鍍CrN與CrN/Cr薄膜提升CoCrNiSi0.3中熵合金抗磨耗及抗腐蝕性質之研究 Study on Improving the Corrosion and Wear Resistance of CoCrNiSi0.3 Medium-Entropy Alloy by Magnetron Sputtered CrN and CrN/Cr Films |
作者: | 張奕淳 Yi-Chun Chang |
指導教授: | 林新智 Hsin-Chih Lin |
關鍵字: | 中熵合金,磁控濺鍍法,CrN薄膜,磨耗試驗,腐蝕試驗,CrN/Cr多層膜, Medium-Entropy Alloy,Magnetron Sputtering,CrN thin film,Wear,Corrosion,CrN/Cr multilayer, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 本研究選取Co、Cr、Ni作為等中熵合金(MEA)體系,加入Si形成CoCrNiSi0.3 MEA。為了進一步提高其抗磨耗及抗腐蝕性,在表面沉積了單層CrN與多層CrN/Cr薄膜。為了提升硬度較低的 CoCrNiSi0.3基材與高硬度 CrN 薄膜之間的附著力,在 CoCrNiSi0.3基材上沉積了 Cr 中介層,以防止基材與薄膜之間因為晶體結構及熱膨脹係數差異過大而產生剝落。本實驗分為四個階段,第一階段改變CoCrNiSi0.3基材之退火時間,分別為15、30及60分鐘;第二階段則選用第一階段最佳參數作為後續鍍膜之基材,並改變CrN沉積時間,分別為2、2.5、3及3.5 小時;第三階段選用第二階段最佳參數,改變CrN沉積溫度,分別為225、250、275及300 oC;第四階段選用第三階段最佳參數,改為沉積CrN/Cr之多層膜,並改變CrN/Cr的層數,分別為1、2、及3層。此外,本研究藉由硬度試驗、磨耗試驗、腐蝕試驗及奈米壓痕等試驗以評估薄膜之性能,並使用低掠角薄膜繞射(GIXRD)、AFM、SEM、EBSD、EPMA與TEM等儀器,以進行成分與結構之分析。
實驗的第一階段我們首先透過改變CoCrNiSi0.3 MEA的退火時間,控制晶粒大小以得到最佳磨耗及腐蝕性質,實驗結果表明,當退火時間達30分鐘時,晶粒大小為17.5μm,可同時擁有良好的抗磨耗及抗腐蝕性質。第二階段我們改變CrN薄膜的沉積時間,實驗結果表明,CrN薄膜呈柱狀晶粒結構,薄膜生長速率約為2.022 μm/h。隨著沉積時間的增加,CrN薄膜厚度的增加和柱狀晶的細化提高了抗磨性和抗蝕性。沉積時間達3小時的CrN薄膜,可具有最佳的抗磨耗性質,磨耗率為2.249 x 10−5 mm3•m−1•N−1,以及最佳的耐腐蝕性,腐蝕電流密度為19.37 μA•cm–2、腐蝕極化阻抗為705.85 Ω•cm2。第三階段改變CrN薄膜的沉積溫度,實驗結果表明,隨著沉積溫度增加,使原子具有更高流動性,使薄膜緻密度逐漸增加,且缺陷密度大幅下降。沉積溫度達300oC的CrN薄膜,具有最佳的抗磨耗性質,磨耗率為0.583 x 10−5 mm3•m−1•N−1,以及最佳的抗腐蝕性質,腐蝕電流密度為4.51 μA•cm–2、腐蝕極化阻抗為857.92 Ω•cm2。第四階段改變沉積CrN/Cr多層薄膜的層數,實驗結果表明,隨著多層薄膜層數增加,添加Cr層導致CrN柱狀晶生長中斷,使晶粒逐漸細化,而多層結構可作為裂縫及腐蝕液傳遞的屏障,並且Cr層可提供良好的韌性、Cr2N過渡層可提升多層薄膜附著性,因此,沉積層數達三層的CrN/Cr多層薄膜,可具有最佳的抗磨耗性質,在2N及4N荷重下磨耗率分別為3.331 x 10−6 mm3•m−1•N−1、1.124 x 10−5 mm3•m−1•N−1,以及最佳的耐腐蝕性,腐蝕電流密度為0.73 μA•cm–2、腐蝕極化阻抗為962.35 Ω•cm2。 綜合以上分析結果,CoCrNiSi0.3 MEA經過磁控濺鍍法沉積CrN/Cr三層多層膜並調控至最佳時間與溫度參數下,能夠大幅提升表面性質,即使增加磨耗試驗之荷重至4N,也不會使薄膜產生剝落,且表面具有極高的疏水性,進一步使抗磨耗及抗腐蝕性質得到提升,達到提升使用性能與延長壽命之目的。 This study selected Co, Cr, and Ni as the equal-atomic medium entropy alloy (MEA) system, and Si was added to form CoCrNiSi0.3 MEA. To further improve its wear and corrosion properties, CrN film was sputtered on the surface. To enhance the adhesion between the low-hardness CoCrNiSi0.3 substrate and the high-hardness CrN film, a Cr interlayer was deposited on the CoCrNiSi0.3 substrate to prevent delamination due to significant differences in crystal structure and thermal expansion coefficient between the substrate and the film. The experiment was divided into four stages, the first stage changed the annealing time of the CoCrNiSi0.3 substrate, which was 15, 30, and 60 minutes, respectively. In the second stage, the best parameters of the first stage were selected as the substrate for subsequent coating, and the CrN deposition time was changed to 2, 2.5, 3, and 3.5 hours, respectively. In the third stage, the optimal parameters of the second stage were selected to change the CrN deposition temperature to 225, 250, 275, and 300 oC, respectively. In the fourth stage, the best parameters of the third stage were selected to deposit the multilayer film of CrN/Cr, and the cycle times of CrN and Cr layers were changed, which were 1, 2, and 3 times, respectively. Furthermore, the hardness test, wear test, corrosion test, and nanoindenter test were used to evaluate the performance of the CrN & CrN/Cr thin film, and instruments such as Grazing Incidence X-ray Diffraction (GIXRD), AFM, SEM, EBSD, EPMA, and TEM were used to analyze the composition and structure. In the experiment’s first stage, we controlled the grain size to obtain the best wear and corrosive properties by changing the annealing time of CoCrNiSi0.3 MEA. The experimental results showed that when the annealing time reached 30 minutes, the grain size was 17.5μm, which could have well wear and corrosion resistance at the same time. In the second stage, we changed the deposition time of the CrN film layer, and the experimental results showed that the CrN film had a columnar grain structure, and the film growth rate was about 2.022 μm/h. With the increase of sputtering time, the increase of CrN film thickness and the refinement of columnar crystals improve wear resistance and corrosion resistance. The CrN film with a deposition time of 3 hours has the best wear resistance, with a wear rate of 2.249 x 10−5 mm3•m−1•N−1, and the best corrosion resistance, with a corrosion current density of 19.37 μA•cm–2 and a corrosion polarization impedance of 705.85 Ω•cm2. The third stage changes the deposition temperature of the CrN film layer. With the increase of sputtering temperature, the atoms enhance mobility, leading to progressive densification of the thin film and a substantial reduction in defect density. The CrN film with a deposition temperature of 300 oC has the best wear resistance, with a wear rate of 0.583 x 10−5 mm3•m−1•N−1, and the best corrosion resistance, with a corrosion current density of 4.51 μA•cm–2 and a corrosion polarization impedance of 857.92 Ω•cm2. The fourth stage changes to the multilayer film that deposits CrN/Cr. With the increase in the number of multilayer films, the introduction of a chromium (Cr) layer disrupts the growth of columnar crystals, leading to a gradual refinement of the grain size. The multilayer structure acts as a barrier against crack propagation and corrosive media, while the Cr layer provides excellent toughness. Moreover, the presence of a Cr2N transition layer enhances the adhesion of the multilayer film. A multilayer film composed of three layers of CrN/Cr has the best wear resistance, with a wear rate of 0.583 x 10−5 mm3•m−1•N−1 and 1.124 x 10−5 mm3•m−1•N−1 under 2N and 4N load, respectively, and the best corrosion resistance, with a corrosion current density of 4.51 μA•cm–2 and a corrosion polarization impedance of 857.92 Ω•cm2. Based on the comprehensive analysis results, it has been found that by depositing a three-layer multilayer film of CrN/Cr on CoCrNiSi0.3 MEA using the magnetron sputtering technique and optimizing the time and temperature parameters, the surface properties can be significantly improved. Even under an increased load of 4N during wear tests, no film delamination occurs, and the surface exhibits high hydrophobicity. This further improves wear resistance and corrosion resistance, achieving the goal of enhancing performance and extending the lifespan. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88372 |
DOI: | 10.6342/NTU202301965 |
全文授權: | 同意授權(限校園內公開) |
顯示於系所單位: | 材料科學與工程學系 |
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