- 學位論文
真空加壓鑄造機對傳統陶瓷燒付鈀銀合金反覆鑄造之影響
Effect on recasting of palladium-silver porcelain alloy by vacuum-pressure casting machine
摘要
研究目的：鈀銀合金是重要的陶瓷燒付金屬。如果能在良好的環境下反覆鑄造，勢必能降低成本而有助於鍵結強度。本研究的目的在探討以真空加壓鑄造機反覆鑄造陶瓷用鈀銀合金的可能性。 材料與方法：鑄造金屬為鈀銀合金Jelstar (J.F.Jelenko., USA)，以磷酸鹽包埋材Fujivest II(G.C., USA)包埋，鑄造機採用真空加壓鑄造機(Castmatic-S, Japan)及傳統水平離心鑄造機(Kerr, USA)。反覆鑄造世代：第一代為全新合金；第二、三、四代的反覆鑄造金屬為50% 前次鑄造的殘餘合金＋50% 新合金。共分8組，每組鑄造3個試片。鑄造體的邊緣縫隙值以3D自動掃瞄儀來測量、以X光繞射儀分析所含之組成、以電子微探儀分析斷面金屬元素的成分重量百分比變化、以微硬度測試儀測量硬度變化、以表面粗糙度測試儀分析表面粗糙度。以two-way ANOVA作統計分析，p <0.05。 結果：所有組的完整鑄造比例都達到100%。在邊緣密合度方面，以全新合金搭配真空加壓鑄造機邊緣縫隙值最好31.1±9.7μm，第四代合金搭配傳統離心鑄造機的結果最差68.5±18.0μm；在邊緣精密度方面，真空加壓鑄造機的各代鑄造體表現較好。以XRD分析成分，所得資料比對結果，特定波峰為鈀、銀的成分。不同鑄造方式與不同的金屬世代對所有金屬的成分重量百分比都沒有顯著差異（p > 0.05）。銦與錫在真空加壓鑄造方式中都沒有減少。以全新合金搭配真空加壓鑄造機氧化層厚度最小3.8±0.3μm，第四代合金搭配傳統離心鑄造機的厚度最大5.3±0.6μm。可以看出傳統離心鑄造機的各代氧化層都較厚，且隨著鑄造次數增加，氧化層有增厚的趨勢。全新合金搭配傳統離心鑄造機的硬度最高179.6±1.7，第四代合金搭配真空加壓鑄造機的硬度最低166.2± 1.4。傳統離心鑄造機的鑄造體有較大的硬度值。以全新合金搭配真空加壓鑄造機表面粗糙值最小1.15 ± 0.18μm，第二代合金搭配真空加壓鑄造機的結果最差2.13 ± 0.47μm。不同的金屬世代與鑄造機對表面粗糙度有顯著差異(p<0.05)。將研究純鈦鑄造的技術應用於陶瓷燒付鈀銀合金上，由於特殊的鑄造環境與設計上的優點，希望使鑄造體有理想的結果，在本實驗中已有預期中的正面成果。 結論：鈀銀合金在反覆鑄造下仍有良好的邊緣密合度，添加50%新合金反覆鑄造的結果顯示成分穩定，顯示鑄造機的進步，使用真空加壓鑄造機來取代傳統離心鑄造機應會有相當不錯的表現。氧化層的變化則需更進一步研究。
並列摘要
Objective : Palladium-silver alloys were important porcelain bonding alloys. The purpose of this investigation was to determine the effect on recasting of palladium-silver porcelain alloy by vacuum-pressure casting machine. Materials & Methods : The casting alloy was Jelstar (J.F.Jelenko., USA) and the phosphate-bonded investment Fujivest II(G.C., USA) was used. The castings were performed in the vacuum-pressure casting machine (Castmatic-S, Japan) and the traditional centrifugal casting machine (Kerr, USA). The initial casting was completed with a totally new alloy. Part of surplus (sprue and button ) alloy removed from the previous casting was weighed, and combined with appreciate new alloy to achieve 50 % weigh ratio for the next casting. The sequence was repeated through three generation. In the study, we used 2 casting machines and repeated casting 4 generation, totally 8 groups. Each group has 3 samples. The marginal fitness of castings was compared by 3D coordinate measuring machine. XRD analyzed the composition of castings. The level of chemical reactivity was evaluated by EPMA. The level of hardness was measuring by microhardness tester. The surface roughness of castings was measuring by surface roughness tester. These values were analyzed with two-way ANOVA, p <0.05. Results : The castability was reach 100% in all groups. The group casting by vacuum-pressure casting machine with new alloy has least marginal gap (31.1±9.7μm). The group casting by traditional centrifugal casting machine with the alloy of forth generation has largest marginal gap (68.5±18.0μm). The repeated casting by vacuum-pressure casting machine showed better result in the aspect of marginal gap. XRD analysis of all samples showed the main components were Pd and Ag. The composition of alloy measuring by EPMA showed no significant differences between repeated castings and casting machines(p>0.05). In and Sn were not lost in vacuum-pressure casting pattern. The thickness of oxidation layer of the group casting by vacuum-pressure casting machine with new alloy was thinnest(1.15±0.18μm). The thickness of oxidation layer of the group casting by traditional centrifugal casting machine with the alloy of forth generation was thickest (2.13±0.47μm). The thickness of oxidation layer of castings by traditional centrifugal casting machine were thicker, and increased through each generation. The group casting by traditional centrifugal casting machine with new alloy has largest VHN(179.6±1.7). The group casting by vacuum-pressure casting machine with the alloy of forth generation has smallest VHN (166.2± 1.4). The hardness of castings by traditional centrifugal casting machine were higher. The group casting by vacuum-pressure casting machine with new alloy has least surface roughness(1.15±0.18μm). The group casting by vacuum-pressure casting machine with the alloy of second generation has largest surface roughness (2.13±0.47μm). The repeated casting and casting machine showed significant differences between surface roughness (p<0.05). Conclusion : The casting machine and repeated casting can effect the outcome of marginal gap, surface roughness and hardness. The automatic casting system of vacuum-pressure vesting machine can provide a safety casting procedure, also can improve the properties of casting. Further investigation is required to determine the alternation of oxidation layer.