Why is tantalum sputtering targets Better?

Chemical compound

Check now

Tantalum carbides (TaC) form a family of binary chemical compounds of tantalum and carbon with the empirical formula TaCx, where x usually varies between 0.4 and 1. They are extremely hard, brittle, refractory ceramic materials with metallic electrical conductivity. They appear as brown-gray powders, which are usually processed by sintering.

Being important cermet materials, tantalum carbides are commercially used in tool bits for cutting applications and are sometimes added to tungsten carbide alloys.[5]

The melting points of tantalum carbides was previously estimated to be about 3,880 °C (4,150 K; 7,020 °F) depending on the purity and measurement conditions; this value is among the highest for binary compounds.[6][7] And only tantalum hafnium carbide was estimated to have a higher melting point of 3,942 °C (4,215 K; 7,128 °F).[8] However new tests have conclusively proven that TaC actually has a melting point of 3,768 °C and both tantalum hafnium carbide and hafnium carbide have higher melting points.[9]

Preparation

TaCx powders of desired composition are prepared by heating a mixture of tantalum and graphite powders in vacuum or inert-gas atmosphere (argon). The heating is performed at a temperature of about 2,000 °C (2,270 K; 3,630 °F) using a furnace or an arc-melting setup.[10][11] An alternative technique is reduction of tantalum pentoxide by carbon in vacuum or hydrogen atmosphere at a temperature of 1,500&#;1,700 °C (1,770&#;1,970 K; 2,730&#;3,090 °F). This method was used to obtain tantalum carbide in ,[12] but it lacks control over the stoichiometry of the product.[7] Production of TaC directly from the elements has been reported through self-propagating high-temperature synthesis.[13]

Crystal structure

TaCx compounds have a cubic (rock-salt) crystal structure for x = 0.7&#;1.0;[14] the lattice parameter increases with x.[15] TaC0.5 has two major crystalline forms. The more stable one has an anti-cadmium iodide-type trigonal structure, which transforms upon heating to about 2,000 °C into a hexagonal lattice with no long-range order for the carbon atoms.[10]

Here Z is the number of formula units per unit cell, ρ is the density calculated from lattice parameters.

Properties

The bonding between tantalum and carbon atoms in tantalum carbides is a complex mixture of ionic, metallic and covalent contributions, and because of the strong covalent component, these carbides are very hard and brittle materials. For example, TaC has a microhardness of 1,600&#;2,000 kg/mm2[18] (~9 Mohs) and an elastic modulus of 285 GPa, whereas the corresponding values for tantalum are 110 kg/mm2 and 186 GPa.[19]

Tantalum carbides have metallic electrical conductivity, both in terms of its magnitude and temperature dependence. TaC is a superconductor with a relatively high transition temperature of TC = 10.35 K.[15]

The magnetic properties of TaCx change from diamagnetic for x &#; 0.9 to paramagnetic at larger x. An inverse behavior (para-diamagnetic transition with increasing x) is observed for HfCx, despite that it has the same crystal structure as TaCx.[20]

Application

Tantalum carbide is widely used as sintering additive in ultra-high temperature ceramics (UHTCs) or as a ceramic reinforcement in high-entropy alloys (HEAs) due to its excellent physical properties in melting point, hardness, elastic modulus, thermal conductivity, thermal shock resistance, and chemical stability, which makes it a desirable material for aircraft and rockets in aerospace industries.

Wang et al. have synthesized SiBCN ceramic matrix with TaC addition by mechanical alloying plus reactive hot-pressing sintering methods, in which BN, graphite and TaC powders were mixed with ball-milling and sintered at 1,900 °C (2,170 K; 3,450 °F) to obtain SiBCN-TaC composites. For the synthesis, the ball-milling process refined the TaC powders down to 5 nm without reacting with other components, allowing to form agglomerates that are composed of spherical clusters with a diameter of 100 nm-200 nm. TEM analysis showed that TaC is distributed either randomly in the form of nanoparticles with sizes of 10-20 nm within the matrix or distributed in BN with smaller size of 3-5 nm. As a result, the composite with 10 wt% addition of TaC improved the fracture toughness of the matrix, reaching 399.5 MPa compared to 127.9 MPa of pristine SiBCN ceramics. This is mainly due to the mismatch of thermal expansion coefficients between TaC and SiBCN ceramic matrix. Since TaC has a larger coefficient of thermal expansion than that of SiBCN matrix, TaC particles endures tensile stress while the matrix endures tensile stress in radial direction and compressive stress in tangential direction. This makes the cracks to bypass the particles and absorbs some energy to achieve toughening. In addition, the uniform distribution of TaC particles contributes to the yield stress explained by Hall-Petch relationship due to a decrease in grain size.[21]

Wei et al. have synthesized novel refractory MoNbRe0.5W(TaC)x HEA matrix using vacuum arc melting. XRD patterns showed that the resulting material is mainly composed of a single BCC crystal structure in the base alloy MoNbRe0.5W and a multi-component (MC) type carbide of (Nb, Ta, Mo, W)C to form a lamellar eutectic structure, with the amount of MC phase proportional to TaC addition. TEM analysis showed that the lamellar interface between BCC and MC phase presents a smooth and curvy morphology which exhibits good bonding with no lattice misfit dislocations. As a result, the grain size decreases with increasing TaC addition which improves the yield stress explained by Hall-Petch relationship. The formation of lamellar structure is because at elevated temperature, the decomposition reaction occurs in the MoNbRe0.5W(TaC)x composites: (Mo, Nb, W, Ta)2C &#; (Mo, Nb, W, Ta) + (Mo, Nb, W, Ta)C in which Re is dissolved in both components to nucleate BCC phase first and MC phase in the following, according to the phase diagrams.[22] In addition, the MC phase also improves the strength of composites, due to its stiffer and more elastic property compared to BCC phase.[23]

Wu et al. have also synthesized Ti(C, N)-based cermets with TaC addition with ball-milling and sintering at 1,683 K (1,410 °C; 2,570 °F). TEM analysis showed that TaC helps dissolution of carbonitride phase and converts to TaC-binder phase. The resulting is a formation of &#;black-core-white rim&#; structure with decreasing grain size in the region of 3-5 wt% TaC addition and increasing transverse rupture strength (TRS). 0-3 wt% TaC region showed a decrease in the TRS because the TaC addition decreases the wettability between binder and carbonitride phase and creates pores. Further addition of TaC beyond 5 wt% also decreases TRS because TaC agglomerates during sintering and porosity again forms. The best TRS is found at 5wt% addition where fine grains and homogeneous microstructure are achieved for less grain boundary sliding.[24]

Natural occurrence

Tantalcarbide is a natural form of tantalum carbide. It is a cubic, extremely rare mineral.[25]

See also

References

Introduction

Tantalum Carbide (TaC) sputtering targets are essential in thin film deposition. These materials are known for their high hardness, heat resistance, and durability. TaC is used to create coatings that perform well in extreme environments. These qualities make it a popular choice in modern industries.

This article will explore the top five applications of TaC sputtering targets. From thermal barrier coatings to corrosion-resistant films, TaC helps improve product performance and reliability.

1. High-Temperature Coatings

Tantalum Carbide (TaC) is widely used for thermal barrier coatings. These coatings protect materials exposed to high temperatures, such as in gas turbines and spacecraft. TaC has an extremely high melting point of °C, making it ideal for these applications.

In aerospace, TaC coatings shield parts from heat stress and oxidation. This helps improve the efficiency and lifespan of engines. In the energy industry, TaC coatings are applied to turbines to reduce thermal fatigue. This extends the operational life of equipment and reduces maintenance costs.

By providing superior heat resistance, TaC sputtering targets are essential for industries that operate under extreme conditions.

2. Hard Coatings for Industrial Tools

TaC sputtering targets are critical for creating hard coatings on industrial tools. These coatings improve the durability and wear resistance of tools such as drills, cutting blades, and molds. TaC&#;s high hardness ensures that tools can withstand intense pressure and friction during use.

In metalworking and manufacturing, TaC-coated tools last longer and perform better. These coatings reduce wear, extending the lifespan of expensive equipment. For example, cutting tools with TaC coatings maintain sharp edges even when working with tough materials like steel or titanium.

By enhancing tool performance, TaC sputtering targets help industries save costs and improve production efficiency.

3. Optical Coatings

Tantalum Carbide (TaC) is a valuable material for creating optical coatings. These coatings are used in lenses, mirrors, and infrared windows. TaC has a high refractive index, which helps improve light transmission and reduce reflection. This makes it ideal for applications where clarity and precision are essential.

In the optics industry, TaC coatings are applied to equipment used in scientific research, military systems, and high-tech imaging devices. For example, infrared cameras often rely on TaC-coated windows to improve performance under harsh conditions. These coatings are also durable, maintaining optical quality even after long-term exposure to heat and wear.

By providing reliable and efficient optical coatings, TaC sputtering targets play a crucial role in advancing optical technology.

4. Semiconductor Thin Films

Tantalum Carbide (TaC) sputtering targets are widely used in the semiconductor industry. TaC coatings are applied to create thin films that protect electronic components. These films provide excellent conductivity and thermal stability, which are essential for the performance of semiconductors.

In chip manufacturing, TaC thin films are used as diffusion barriers. They prevent the migration of materials like copper, ensuring the reliability of microchips. TaC also supports high-precision deposition, which is crucial for creating uniform and defect-free layers on delicate electronic components.

With its durability and precision, TaC plays a key role in improving semiconductor devices used in computers, mobile phones, and other advanced electronics.

5. Corrosion-Resistant Coatings

Tantalum Carbide (TaC) sputtering targets are also used to create corrosion-resistant coatings. These coatings protect equipment and structures from chemical damage in harsh environments. TaC&#;s chemical inertness makes it ideal for preventing corrosion caused by acids, alkalis, and other reactive substances.

Industries such as petrochemicals, pharmaceuticals, and energy rely on TaC coatings for their critical systems. For example, reactors, storage tanks, and pipelines often use TaC-coated surfaces to withstand corrosive materials. These coatings not only reduce maintenance costs but also extend the lifespan of expensive equipment.

By providing superior corrosion resistance, TaC sputtering targets help ensure the durability and reliability of industrial systems.

Conclusion

Tantalum Carbide (TaC) sputtering targets are critical for creating advanced coatings across various industries. From thermal barriers and hard coatings to optical films, semiconductor layers, and corrosion-resistant surfaces, TaC plays an essential role. Its unique properties, including extreme hardness, high melting point, and chemical inertness, make it indispensable in high-performance applications.

As industries continue to innovate, the demand for reliable materials like TaC will grow. Companies like Stanford Advanced Materials (SAM) provide high-quality TaC sputtering targets to meet these needs. With expertise in advanced materials, SAM supports industries looking for durable and efficient solutions. For more information, explore our product offerings and learn how TaC can enhance your projects.

Contact us to discuss your requirements of tantalum sputtering targets. Our experienced sales team can help you identify the options that best suit your needs.