# High-Pressure Sensors Based on Laser-Manufactured Sintered Silicon Carbide
## 1 Introduction  
Laser material processing represents a powerful tool in the modern manufacturing industry. Laser cutting is the most common industrial application of lasers, as well as welding, drilling, and marking processes, which have reached the right maturity to be accepted as standard tools in modern industry. Moreover, in recent years laser processing of materials also opened new perspective in additive manufacturing and micro-fabrication [1]. This trend is driven by the development of new applications as well as the increasing adoption of advanced ceramics in already established applications due to superior material and performance properties. However, it is worth noting that these properties are also the ones that do not allow obtaining accurate geometries using conventional machining techniques in a simple, cheap, and time-effective way [2]. In this context, lasers appear to be a promising technology with respect to ordinary material removal methods, because the machining operation is carried out without any contact between the laser system and the part, therefore ensuring the elimination of cutting forces, tool wear, and machine vibration [3]. In fact, the process efficiency depends on the thermal and optical properties of the material, allowing also hard or brittle materials, such as ceramics, to be machined. Moreover, lasers can be used for different applications, from the ablation of advanced ceramics [4], to the hardening of structural materials [5], to the joining of hybridstructures [6], as well as to the milling of composites [7], therefore demonstrating a very high versatility. Compared to other techniques, it is worth to mention that laser represents a unique manufacturing tool for ultra-hard material processing, such as diamond [8]. Indeed, laser allows to locally heat and ablate diamond allowing the realization of optics tailored to the specific application [9], as well as to induce a local transformation of diamond into graphite for the fabrication of all-carbon sensors with novel contact structures [10; 11; 12]. Silicon Carbide (SiC) represents the unique solid compound of silicon. Since the end of the 19 th century, mass-produced SiC powder has been used as an abrasive in grinding wheels and abrasive applications in general. In addition, one of the early application of SiC ceramics was as high-durable brake discs for high-performance vehicles. With modern technology, high-quality SiC ceramics are produced [13]. Such materials have peculiar chemical and physical properties, such as high strength, ultra-high hardness, high elastic modulus, high resistance to thermal shock, low thermal expansion, superior chemical inertia, high thermal conductivity, and excellent corrosion resistance [14]. For these reasons SiC finds application in the manufacture of high precision machine parts. SiC ceramics are widely used, for example, in the automotive industry for the manufacture of brakes and clutches [15], but are also used for the fabrication of plates in bulletproof vests. In addition, due to its physical properties, one of the first applications of SiC was as lighting arrester in electric power distribution systems. Nowadays, modern microelectronics technology in advanced semiconductor industries has also made it possible to apply SiC in crystalline form for the manufacture of electronic components able to operate in high power and high frequency fields. SiC devices find application especially in harsh environments where silicon shows its limits mainly due to a reduced bandgap compared to SiC. Moreover, due its excellent characteristic, most of research works are related to the fabrication of micro-electro mechanical systems (MEMSs) based on crystalline SiC. The high hardness and low fracture toughness make crystalline SiC (c-SiC), as well as sintered SiC (S-SiC), difficult to machine. In fact, conventional diamond grinding or turning is characterized by high cost and high wear of diamond tools [16].