- 學位論文
含廢玻璃之澆注型複材之強度改善研究
Study on Strength Improvement of Castable Composites Containing Waste Glass
摘要
本研究包括兩個階段，一是在改進前李廷恩之碩士論文(7/2019)[1]提出含廢玻璃之澆注型複材結構件配方(T2-2)之強度，此配方目標為應用於中溫(650-800℃)固態燃料電池之結構件。研究中，選用與T2-2相同之原料系統，包含棕色廢棄玻璃顆粒、廢棄之封裝玻璃(G11A5)粉末，廢棄之碳化矽磨料及波特蘭Ⅰ型水泥作為原料。本研究為尋找更佳的原料配比，優化結構件之抗折強度。先以田口法(Taguchi method)作為實驗規劃之方法，透過L9直交表，選取四種控制因素，每個因素具有三個水準值，以優化其抗折強度為目標，在完成L9表設計之實驗後，透過信噪比分析(S/N ratio)分析實驗數據，確認四種控制因素對抗折強度之影響程度，並找出能改進強度的水準值。經過田口法之優化後，經800℃/1h燒結後樣品之抗折強度為2.43 MPa (T2-2為0.54 MPa)，壓縮強度為3.22 MPa，雖有改善但不盡理想，觀察其微結構發現在800℃煅燒後有因燒結收縮的大裂縫而造成強度損失，在1000℃強度損失的原因則是多了粗顆粒玻璃，在高溫時會形成發泡(bubbling)結構。此外，若低熔點之G11A5玻璃含量過多會使樣品在1000℃熔化崩塌。為了改善前述缺點，在第二階段的優化實驗中，將澆注材分為骨材和漿料(細粉+水)兩部分討論，骨材選用廢棄之碳化矽磨料及有較高熔點之低鹼玻璃(GC)，透過顆粒堆積理論決定澆注材中骨材的比例，以期在和漿料混合後有最好的流動性及最高800℃燒結後之強度。透過漿料黏塑性測試及乾燥並煅燒後之微結構決定漿料的成分，然後將已確定成分之骨材及漿料以不同比例混合、成型、煅燒後進行強度測試。將含75vol%骨材-25 vol%細粉之配方命名為N75，以此類推N65和N55。這三配方之800℃煅燒後抗折強度都在7~9 MPa之間，1000℃煅燒後抗折強度都在11~13 MPa之間，相較原T2-2配方及經過田口法優化後之T2-2配方皆有大幅提升。N系列之配方的抗壓強度均高於10 MPa，已達SOFC結構件所需的工程強度。
並列摘要
This research includes two parts. The first aims to improve the strength of castable formula (T2-2) containing waste glass, which was proposed by Li (7/2019) [1]. The goal of this task was used to be IT (650-800°C) structural parts in SOFC. This study crushed 4 waste glasses, and mixed with waste SiC abrasive and Portland cement (type Ⅰ). In order to find a better mixture to optimize strength of structural parts, Taguchi method was used as the experimental planning method. Through L9 orthogonal array, four control factors were selected, and each factor had three levels. With a goal of improving its bending strength, we completed the experiment of a L9 table design and analyzed the experimental data through S/N ratio analysis, and confirmed the influence of the level of four control factors on the strength. Finally, we found appropriate levels of control factors which could improve the strength. However, the bending strength of the optimized formula after 800℃/1h sintering was 2.43 MPa (T2-2 was 0.54 MPa) and the compressive strength was 3.22 MPa, which were unsatisfactory. By analyzing the microstructures, large cracks in matrix caused by sintering shrinkage appeared after sintering at 800°C, which would cause the strength loss. The reasons also partially by melting and bubbling of coarse glass particles at high temperatures, also by the low melting point of G11A5 which limited the usage of the waste glass, because too much glass with a low melting point would cause the sample melting at 1000°C. In order to improve the aforementioned shortcomings, in the second part of the optimization experiments, two types of raw materials for castable, either aggregates or slurry (fine powder + water) were used. The aggregate contained waste SiC abrasive and low-alkali glass particles with a higher melting point. The proportion of aggregates was determined by rule of mixture (a particle packing theory), so to achieve a highest density and better flowability. Selections of the proportion of slurry was determined by rheology test of the slurry, and the microstructure of the dried and calcined parts. Finally, the aggregates and slurry of the determined composition were mixed in different proportions and calcined for strength testing. The samples with 75 vol % aggregates-25% fine powder was named “N75”, and the others “N65” and “N55” were tested after calcination at 800°C. The bending strength of all was between 7 and 9 MPa. Those after calcination at 1000°C were between 11 and 13 MPa, which were significantly higher than the strength of original T2-2 formula and the modified T2-2 formula by Taguchi method. The compressive strengths of the N-series samples were higher than 10 MPa, which have met the required engineering strength of SOFC structure parts.