**3.1 Ceramic fibers for ballistics**

The ceramic fibers possess excellent physical and mechanical properties (e.g., high-strength and high-modulus properties). Due to their high resistance to very high temperatures, these fibers had found usage in the aerospace and rocket industry in manufacturing objects able to sustain the high level of physical and mechanical load [14]. Because these fibers have a large diameter, they can be used as uni-directional tapes in the prepreg manufacturing process of clay-fibers composites. Characteristics of composites intended for ballistic protection largely depend on fiber type and layer orientation. The ceramic fibers layer tends to be strongest when the load acts along the direction in which the fibers are laid. The impact of the projectile causes the development of longitudinal and transverse waves, which help define the mode of failure [15]. Also, many kinds of research prove that the direction and structure of fibers have an effect on ballistic resistance properties. The development of ballistic resistance plates

with different fibers and fabrics have been explored for performance. Woven fabrics were found to provide better mechanical properties than unidirectional fabrics [16].

The ceramic fibers are usually made from large-diameter monofilaments tungsten-core wire and vapors of ceramic materials (e.g., boron and silicon carbide) in the vapor deposition process, and spinning method to obtain alumina ceramic fibers [17]. The physical and mechanical properties of different ceramic fibers are shown in **Table 1**.

Unlike other fibers used in the manufacture of composites to increase the ballistic protection of soldiers and vehicles (poly aramids, glass, aromatic polyesters, and UHMWPE), ceramic fibers can withstand temperatures up to 12,000°C. The materials for ballistic protection do not need to withstand such high temperatures, and the primary need is to prevent penetration of projectile. Fabrics made of ceramic fibers for the purpose of making composite materials in order to increase ballistic protection can be two-dimensional (2D) and three-dimensional (3D) fabrics. Two-dimensional woven fabrics are mainly used in the production of composites for ballistic applications. In laminated ballistic composites, different types of yarns that are intertwined can be combined, i.e. different yarns that extend along the length of the fabric (warp) and yarns that go from edge to edge (weft) based on a predefined pattern. The combination of layers that can be seen in one or more directions improves ballistic resistance and puncture resistance, resulting in multiple 2D woven fabrics. Multiple 2D woven fabrics can be layered to provide ballistic and puncture resistance, in particular by enhancing the ballistic and stabbing resistance, especially by decreasing the back-face deformation. The disadvantage of 2D woven fabric is that there is a high possibility of sequential delamination due to projectile impact and weakening of the adhesion caused by the deterioration of the matrix [18, 19]. The presence of Z-oriented fibers in 3D enhances in-plane properties due to the bias yarn layers so that could be the solution for the delamination problem. **Figure 1** is shown the various weave constructions of 2D and 3D fabrics used in ballistic composite production.

**Table 2** shows the density and Hugoniot elastic limits (HEL) of different ceramic fibers which can be used in the production process of ballistic protection products.

From the aspect of economic profitability, the use of alumina ceramic fibers is the most favorable among advanced ceramics fibers with high physical and mechanical properties. However, by the analysis shown in **Table 2**, using alumina (Nextel 3 M) has the lowest projectile penetration protection efficiency of all the materials shown but composites made on the basis of these fibers have the lowest efficiency of all the listed materials. Carbides are the hardest ceramics but do not withstand high impact pressures due to an amortization process that weakens the ceramic [20]. The Beryllium-oxide and Magnesia.


#### **Table 1.**

*The physical and mechanical properties of alumina and SiC fibers.*

*Ballistic Composites, the Present and the Future DOI: http://dx.doi.org/10.5772/intechopen.102524*

### **Figure 1.**

*Weave constructions of 2D and 3D fabrics.*


#### **Table 2.**

*The density and Hugoniot elastic limits (HEL) of different ceramic fibers.*
