Calcium is an alkaline earth metal with an atomic weight of 40.08, an outer electron configuration of 4S², a density (20℃) of 1.55 g/cm³, a melting point of 839 ± 2℃, and a boiling point of 1484℃. The vapor pressure of calcium is related to temperature as follows:
lnpCa = 25.7691 - 20283.9T⁻¹ - 1.0216lnT
Where pCa is the vapor pressure of calcium (Pa), and T is the temperature (K). Silicon reacts with calcium to form three compounds: CaSi, Ca₂Si, and CaSi₂. CaSi (41.2% Si) is stable at high temperatures. Ca₂Si (29.5% Si) is a peritectic compound formed between Ca and CaSi below 910℃. CaSi₂ (58.36% Si) is a peritectic compound formed between CaSi and Si below 1020℃. The phase composition of industrially produced silicon-calcium alloys is approximately 77% CaSi2, 5%–15% CaSi, <20% Si free, and <8% SiC. Silicon-calcium alloys containing 30%–33% Ca and approximately 5% Fe have a density of approximately 2.2 g/cm3 and a melting temperature range of 980–1200℃.
