free iron oxide

例句：

1. 1. The process of free iron oxide formation is complex and requires careful control.
   自由铁氧化物的形成过程复杂，需要严格控制。
2. 2. The use of free iron oxide in paints has been a topic of debate for decades.
   自由铁氧化物在油漆中的使用已经是一个讨论了几十年的话题。
3. 3. Researchers are exploring the potential applications of free iron oxide in various industries.
   研究人员正在探索自由铁氧化物在各种行业中的潜在应用。