摘要
本研究針對離心鑄造製得SK300及SK500雙合金料管之結構特性進行量測。SK300雙合金料管主要用於180~200 °C之尼龍玻纖射出成型，其料管內壁耐磨層採用鎳基合金添加15 wt.%鉻金屬之設計, 'Times New Roman';">若因應較高溫（350~400 °C）塑料射出成型的需求，則選用鎳基合金添加10 wt.%鉻金屬及15 wt.%碳化鎢顆粒作為SK500雙合金料管內壁耐磨層之組成設計。鎳基合金耐磨層基地以富鎳之γ-Ni枝晶組織為主，並含有Cr7C3, Ni3Si等化合物散佈在基地中。對比SK300雙合金料管，SK500雙合金料管內側批覆層含有碳化鎢顆粒，造成耐磨層硬度提升，亦細化耐磨層組織晶粒尺寸，從而使SK500雙合金料管具較佳之磨耗阻抗。SK500雙合金料管內壁塗層組織之平均硬度略高於SK300雙合金料管，基於碳化鎢顆粒的散佈，使得耐磨層硬度值變動性大。值得一提，SK500雙合金料管內壁塗層聚集較多數量之碳化鎢顆粒，此現象對於批覆塗層之磨耗阻抗有相當大的助益。簡而言之，SK500雙合金料管對高溫塑料射出成型有相當的應用潛力。
關鍵詞：離心鑄造、雙合金料管、耐磨層、鎳基合金、碳化鎢、磨耗阻抗
Abstract
This study examines the structural properties of SK300 and SK500 bimetallic tubes fabricated by the centrifgual casting. The SK300 bimetallic tube is used for injection molding of glass fiber-filled nylon at 180-200 °C, and its wear-resistant layer on the inside of the tube is designed and composed of a nickel (Ni)-based alloy reinforced with 15 wt.% chromium (Cr). For higher-temperature (350-400 °C) plastic injection molding, a Ni-based alloy reinforced with 10 wt.% Cr and 15 wt.% tungsten carbide (WC) is used to the inside wear-resistant layer for the SK500 bimetallic tube. The microstructures of Ni-based alloy wear-resistant layer is mainly composed of Ni-rich γ-Ni dendrite structure, with Cr7C3, Ni3Si compounds distributed in the matrix. Unlike the SK300 bimetallic tube, the inner coating layer of the SK500 bimetallic tube contains WC particles, which enhance the hardness of the wear-resistant layer and refine the grain size. Consequently, the SK500 bimetallic tube shows a better wear resistance. The average hardness of the inner coating layer for the SK500 bimetallic tube is slightly higher than that for the SK300 bimetallic tube. The hardness value of the wear-resistant layer for the SK500 bumetallic tube, however, shows a great deal of variability due to the presence of the WC particles. It should be noted that a larger number of WC particles accumulate near the surface of the coating layer in the SK500 bumetallic tube, contributing significantly to its wear resistance. In summary, the SK500 bumetallic tube displays great potential for application in high-temperature plastic injection molding.
Keywords: Centrifugal casting, Bimetallic tube, Wear-resistant layer, Ni-based alloy, Tungsten Carbide