Reactive YAG Laser Sintering of Gradient Functional Film Made of Hard Boron Carbide

本文研究了以石墨和硼粉为基体的碳化硼（B_4C）的反应激光烧结。碳化硼（B_4C）是一种硬质材料，有望用作抛光粉，但烧结困难，利用率不高。本工作利用激光的热作用，使碳化硼与基体形成粘附，并在基体上形成梯度功能薄膜。首先，用YAG激光照射石墨和硼粉的混合物。并对烧结材料进行了X射线衍射分析。用这种方法合成了碳化硼（B_4C）。接下来，将混合物铺展在基材上，并且YAG激光束在基材上扫描。碳化硼薄膜的硬度为16 GPa。最后，将该方法应用于大长径比微型碳化硼零件的制造。通过与其它陶瓷复合，有望提高膜的硬度。

This research work deals with reactive Laser sintering of boron carbide (B_4C) on a substrate from mixture of graphite and boron powder. The boron carbide (B_4C) is a hard material, therefore, it is expected to apply for polishing powder However, it is difficult to sinter, the material is not used sufficiently. It is expected to become adhesion between the boron carbide and the substrate and expected to produce gradient functional film by the heat of the Laser on the present work.At first, the mixture of the graphite and boron powder is irradiated by the YAG Laser beam. And the sintered material is analyzed by X-ray diffraction. Boron carbide (B_4C) is composed by this method. Next, the mixture is spread on the substrate, and the YAG Laser beam is scanning on the substrate. The hardness of the boron carbide film is 16 GPa. At last, this method is applied for the producing high aspect ratio micro parts made of boron carbide. The hardness of the film is expected to increase by composing by other ceramics.