Design and anti-penetration performance of TiB/Ti system functionally graded material armor fabricated by SPS combined with tape casting

To improve its anti-penetration performance under high-velocity impact loads, a simple and efficient method according to the acoustic impedance matching principle is established to design the structure of TiB/Ti system functionally graded material (FGM) armor. Before the structural design, a series of TiB/Ti composites with different TiB contents are rapidly fabricated by tape casting combined with spark plasma sintering (SPS) to obtain their basic mechanical parameters. The detailed characterizations demonstrate that the acoustic impedance of the TiB/Ti composites increases moronically with TiB content, but it becomes less pronounced at high TiB content. According to the linear fitting of acoustic impedance, the relationship between acoustic impedance and TiB content can be divided into three segments, corresponding to the TiB contents of 5–40 vol%, 40–70 vol% and 70–80 vol%. Consequently, the slopes of the three segments are 0.3226, 0.2031 and 0.0778, respectively. Herein, two types of quasi-continuous TiB/Ti armor with 16 sequential gradient layers based on the above results are designed and fabricated. As a result, the FGM armor possesses excellent anti-penetration performance and secondary strike ability by optimizing the acoustic impedance matching, as revealed by the ballistic test. Besides, the penetration resistance of FGM armor with a uniform gradient of acoustic impedance is better than that with a uniform gradient change of TiB content.