Fig. 7. Shown is a binary phase diagram of the Si-O system.
图7. 所示为Si-O体系 的二元相图。
brown, amorphous product SiOx-1 sity: 2.15 g/cm3
, (den- ). In a
vacuum, it continues to vaporize, resulting in the condensation of the amorphous SiOx (0 < x < 1), the proper- ties of which can be explained depending on the vaporization conditions. During aging and annealing, SiOx
degenerates into clusters of Si and SiO2 up to 1020 cm-3 the rate of condensation, the О2 , which contain
has neither a fixed melting nor fixed boiling point (∆H 0Verd. = 240–380 kJ mol-1
of the paramagnetic centers. Silicon oxide ). Te appearance of SiOx
depends on pressure and other factors.
Silicon oxide undergoes partial oxidation when it is heated in air. When the SiO2
following components: silicon, C, Н2
is reduced, silicon oxide forms with the , hydrocarbons.
Figure 7 shows the Si-O system. A hypothetical SiO
phase is formed at temperatures of between around 1,180C and 1,720C. Following analyses conducted by Brewer
and Edwards, it was concluded that the phase transition Si(s)
+SiO2(s)➞ 2SiO(s) of the disproportionated SiO mixture
occurs at a fixed SiO phase. Later, the existence of a phase formed in this way was confirmed by Brewer and Greene through the reaction of Si and with excess SiO2
at the silicon
melting point (around 1,417C). Te hypothetical SiO phase was shown in the phase diagram. A subsequent analysis conducted by Ekhult and Carlberg confirmed the existence of this phase in the equilibrium between SiO2
and liquid Si
through a comparison of the measured solubility/concentra- tion of oxygen in the silicon with theoretical calculations. It also was determined that, due to a concentration gradient, the oxygen concentration is too low in the liquid Si in superposi- tion with SiO2
.
On the basis of this theory, it can be described using the following equations that SiOx can take the form of a white film:
Si(s) + SiO2(s) → 2 SiO(g)
SiO2(s) + Reduktionsmittel (Si,C,H2 SiOg kondensiert bei Abkühlung in
(3) ,Cm Hm ) → SiO(g) SiO(x-1) verdampft im Vakuum weiter zu (4) SiOx
Proposed solution In a joint project between G. Siempelkamp GmbH &
Co. KG and ASK Chemicals GmbH, the possible underly- ing mechanisms were investigated and potential solutions for reducing defects sought.
(5) 点（∆H(Verd.)^0 = 240–380 kJ mol-1
的簇合物，包含多 达1020cm¬¬¬-3 的顺磁中心。硅氧 化物既没有固定熔 点，也没有固定沸 ）。SiOx
的外观
取决于冷凝的速率、O2压力和其他因素。在空气中 加热时，硅氧化物会被部分氧化。当SiO2 硅、C、H2
还原时，在
、碳氢化合物作用下产生硅氧化物。 图7所示的是Si-O体系。在温度介于约1180C 和1720C之间时，出现假设的SiO相。布鲁尔 （Brewer）和爱德华（Edwards）进行的后续分析表 明，歧化的SiO混合物的相变 Si(s)
+ SiO2(s) → 2SiO(s) 发
生在固定的SiO相。之后，布鲁尔（Brewer）和格林 （Greene）通过Si与过量SiO2
在硅熔点（约1417C）
时发生的反应证实了以该方式形成的一种相的存在。 相图中展示了假设的SiO相。由埃克胡尔特（Ekhult） 和卡尔伯格（Carlberg）进行的后续分析通过比较硅 中测得的氧溶解度/浓度和理论计算，证实了在SiO2 和液态Si之间的平衡中存在该相。同时，该研究还表 明，根据浓度梯度，在液态Si中与SiO2 过低。
叠合的氧浓度
根据上述原理，可以使用下列反应式说明SiOx为何 可能以白膜的形式出现： Si(s)
+ SiO2(s) → 2 SiO(g) (3) SiO2(s) +〖还原剂 (Si,C,H2 SiOx ,Cm Hm
SiOg (→通过冷却冷凝 ) SiO(x-1) (5)
推荐解决方案
辛北尔康普有限公司与亚世科化学有限公司的联 合项目旨在研究该缺陷形成的潜在机制并寻找可能的
December 2014
FOUNDRY-PLANET.COM | MODERN CASTING | CHINA FOUNDRY ASSOCIATION | 65 )→SiO(g) (4) (→在真空中继续蒸发
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