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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/2538

    Title: 碳鋼與鋁-矽-鎂合金反應之機制探討
    Authors: 涂書豪;Shu-hao Tu
    Contributors: 機械工程研究所
    Keywords: A356.2合金;滑石粉;鋁鎂合金;鋁矽合金;碳通道;氧化膜;talcum powder;Al-Mg alloy;oxide film;carbon channel;Al-Si alloy
    Date: 2005-07-25
    Issue Date: 2009-09-21 11:49:44 (UTC+8)
    Publisher: 國立中央大學圖書館
    Abstract: 本研究以1040與1020作為模具模擬材料,鋁湯部份分別採用純鋁、鋁鎂合金、鋁矽合金及A356,分別探討表面粗糙度帶入氧化膜、碳鋼中含碳量以及碳鋼表面噴覆滑石粉對鐵-鋁化合物生長的影響;接著再探討鋁湯中含有鎂、矽元素對於鐵-鋁化合物生長的影響。 實驗結果顯示: (1)碳鋼表面粗糙度帶入的空氣與氧化膜會形成隔絕層,隨著時間增加,由於氧化鋁膜與鋁湯的熱膨脹係數差異,導致氧化鋁膜碎裂,使得鋁湯直接接觸碳鋼表面。 (2)鋁原子沿著肥粒鐵晶界擴散進入肥粒鐵中,然而在鐵-鋁化合物生長過程中,沃斯田鐵含有的碳會擴散,並且堆積在氧化膜上,或者是在堆積的過程中被正在生長的鐵-鋁化合物包覆起來形成碳通道。 (3)鋁湯中所含的矽會與氧化鋁膜反應並分解氧化鋁膜,使得在初期碳鋼較快接觸到鋁湯,但隨時間增加,矽原子擴散至碳鋼基地與鐵-鋁化合物介面之間形成碳化矽,使得鐵-鋁化合物生長受到障礙,因此長時間的生長趨勢減緩。 (4)湯中所含的鎂極易與氧化鋁反應形成尖晶石(spinel),使得在鐵-鋁化 合物與鋁湯的介面之間受到阻礙。 (5)碳鋼表面噴覆滑石粉,能夠有效的阻擋鋁湯直接接觸碳鋼表面。 (6)在A356合金中,在初期容易產生多元氧化物,降低了熱裂的可能性,使得在初期所產生鐵-鋁化合物厚度相當小;之後在碳鋼基地與鐵-鋁化合物介面之間則是鋁湯以及碳鋼中所含矽原子扮演阻礙的角色。 This study used 1040 and 1020 carbon steels to simulate the materials of molds, and the aluminum melt adopted pure aluminum, Al-Mg alloy, Al-Si alloy and A356 separately. The growing of the Fe-Al compound was influenced respectively by the surface roughness formed oxide film, the carbon content of the carbon steel and sprayed talcum powder on the surface of the carbon steel and then investigated the influence of the magnesium and silicon contained in the aluminum melt. Experimental results show: 1. It would form the barrier layer that was caused by the surface roughness of the carbon steel. With time increased, because the difference of the thermal expansion factor among aluminum oxide film and aluminum melt led to the crack of the aluminum oxide film, and the aluminum melt contacted the surface of the carbon steel directly. 2. Aluminum atoms diffused into ferrite along the ferrite grain boundary. During the growing of the Fe-Al compound, the carbon contained in the austenite that diffused, and stacked in the oxide or wrapped by the growing Fe-Al compound then formed the carbon channel. 3. The silicon contained in the aluminum melt reacted with the aluminum oxide film and dissolved it. In the initial stage, it made the carbon steel to contact the aluminum melt faster. But with the time increased, the silicon atoms diffused into between the carbon steel substrate and the Fe-Al compound then formed silicon carbide. It obstructed the growing of the Fe-Al compound and retarded the trend of growing time in long period. 4. The magnesium contained in the aluminum melt was apt to react with the aluminum oxide and formed spinel. It hindered between the Fe-Al compound and the aluminum melt. 5. Coating the talcum powder on the surface of the carbon steel can prevent the aluminum melt to contact the surface of the carbon steel effectively. 6. In the A356 alloy, it was apt to form the diverse oxide in the initial stage and decrease the probability of the thermal cracking. It made the thickness of the Fe-Al compound very thin in the initial stage. The aluminum melt and the silicon contained in the carbon steel retarded between the interface of the carbon steel substrate and the Fe-Al compound.
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