black core meaning in Chinese

黑心斑

Originally , it was believed that these rubies would hardly prove suitable for use in jewellery , since untreated mong hsu ruby crystals actually display two colours : a purple to black core and a bright red periphery
的小城镇。原本蒙苏生产的红宝石是不够格当珠宝的，因为其未经处理的原石呈现两种颜色：紫至黑色的核心及鲜红色的边。
The studies indicate that different content of pyrophyllite and dolomite can cause the following three cases : ( 1 ) making the refractory point decrease linearly and , to some extent , influencing the microstructure and properties of sintered body ; ( 2 ) acceleratingmullite formation during sintering , reducing thermal expansion coefficient of bond , reinforcing the matching nature and improving the flexural strength and shock strength ; ( 3 ) preventing sic grinding tool from generating black core , expanding suitable sintering temperature range of sic grinding tool
同时，也不同程度地影响了磨具烧结体的微观结构和性能； ( 2 )可促进在烧结过程中莫来石的形成，降低结合剂的热膨胀系数，加强了结合剂与磨料的匹配性，提高了磨具的抗折强度和抗冲击强度； ( 3 )在一定温度范围内还可防止碳化硅磨具出现黑心现象，拓宽了碳化硅磨具的烧结温度适应范围。