The process of Vacuum Hot Pressing is used to densify ceramic materials by utilizing thermal and mechanical energy, resulting in high-density ITO ceramic targets with densities ranging from 91% to 96%. The process involves heating a mold, adding samples and setting the mold on a heating plate, while controlling the melting temperature and time. The samples are melted, hardened, cooled and finally the finished product can be taken out.
\n\n\n\nHot isostatic pressing (HIP) is an alternative to pressureless sintering that requires a lower sintering temperature (generally 0.5 to 0.7 times the melting point of the material) and achieves complete densification. This technique is beneficial for controlling structure, inhibiting grain growth, and obtaining a uniform, isotropic structure. When preparing ITO targets by hot isostatic pressing, the ITO solid solution powder must first be reduced in a reducing atmosphere (such as a mixture of H2, N2 and H2) at a temperature of 300 to 500℃. The reduced powder is then processed by molding or cold isostatic pressing to obtain a preform, placed in a stainless steel container with insulating material between them, and vacuum sealed. The sealed container is then placed in a hot isostatic pressing furnace, where it is heated at 800 to 1050℃ at 50 to 200MPa for 2 to 6 hours to prepare the ITO target material.
\n\n\n\nNormal temperature sintering is a target preparation method that was developed in the early 1990s. This method involves mixing In2O3 powder (with a certain tap density) and SnO2 powder to prepare a slurry for mud casting, followed by long-term dehydration and degreasing treatment at 300 to 500°C. The preform is then sintered in a pure oxygen or air atmosphere, at a pressure above 1 atmosphere and a sintering temperature of 1450 to 1550 °C.
\n\n\n\nCold isostatic pressing (CIP) is a process that utilizes rubber or plastic as a covering mold material at normal temperature, with a pressure medium of liquid transmitting ultra-high pressure. The ITO powder is then pressed into a large ceramic preform under a low-pressure oxygen atmosphere, and sintered in a pure oxygen environment of 0.1 to 0.9 MPa at a temperature of 1500 to 1600°C. This method can theoretically produce a ceramic target with a density of 95%.
\n\n\n\nThe hot pressing method is a process in which pressing molding and thermal sintering are performed simultaneously . The advantages of this process are:
\n\n\n\n(1) During the hot pressing process, since the powder is in a thermoplastic state, the deformation resistance is small, and plastic flow and densification are easy, so the required molding pressure is small.
\n\n\n\n(2) Simultaneous heating and pressure are beneficial to the contact, diffusion and flow between powder particles, lowering the sintering temperature and shortens the sintering time, and inhibits grain growth.
\n\n\n\n(3) The hot pressing method makes it easy to obtain a sintered body with a density close to the theoretical density and a porosity close to zero, and a fine-grained structure is easily obtained.
\n\n\n\nThe main disadvantages of this approach are :
\n\n\n\n(1) Due to the limitations of hot pressing equipment and mold size, the obtained target size is small. The current maximum target size is 400×300mm.
\n\n\n\n(2) This method has high requirements for mold materials (generally high-purity and high-strength graphite). Moreover, hot pressing equipment needs to be imported, which is not suitable for industrial continuous production. The production efficiency is low and the cost is high.
\n\n\n\n(3) The uniformity of target grains is poor.
\n\n\n\nHot isostatic pressing is the most commonly used method to prepare ITO sputtering targets. It has the following advantages:
\n\n\n\n(1) It can overcome the shortcomings of hot pressing in graphite molds.
\n\n\n\n(2) Under heating and pressurization, the product is pressurized in all directions at the same time, so that the resulting product has a very high density (close to the theoretical density).
\n\n\n\n(3) Hot isostatic pressing combines the pressing and sintering process and reduces the sintering temperature, resulting in improved physical and mechanical properties of the product, while avoiding grain growth.
\n\n\n\nThe main disadvantages of this approach are :
\n\n\n\n(1) The target size is limited by the equipment pressure and cylinder size, making it difficult to prepare large-size targets.
\n\n\n\n(2) The equipment is expensive and the investment cost is high.
\n\n\n\n(3) Low production efficiency and high production costs make products uncompetitive.
\n\n\n\nThe main advantages of the normal temperature sintering method are :
\n\n\n\n(1) The size of the target material is not limited by the equipment, and large-size targets can be produced.
\n\n\n\n(2) Low equipment investment, low production cost, high production efficiency, excellent target performance, and easy industrial production.
\n\n\n\n(3) This method is suitable for the performance requirements of high-end display coating targets.
\n\n\n\nIts disadvantages are :
\n\n\n\n(1) This sintering method is the most complex compared to other methods, as it requires the addition of sintering aids in order to achieve a dense sintered body. Unfortunately, these sintering aids are difficult to remove from the sintered body, resulting in a reduction in product purity.
\n\n\n\n(2) Meeting the strict requirements for shape, particle size and particle size distribution of the powder generally requires ball milling, airflow milling and sedimentation classification of the powder.
\n\n\n\n(3) The targets produced are generally thin.
\n\n\n\nThe advantages of preparing ITO targets by cold isostatic pressing are:
\n\n\n\n(1) Compared with mechanical pressing, cold isostatic pressing has a large pressure and the workpiece is evenly stressed, making it especially suitable for pressing large-sized powder products.
\n\n\n\n(2) Pressed powder products have the advantages of high density and uniformity.
\n\n\n\n(3) Pressed powder does not require adding lubricant, etc.
\n\n\n\n(4) The production cost is low and suitable for mass production. However, the use of hyperbaric oxygen makes the process dangerous.
\n", "summary": "The process of Vacuum Hot Pressing is used to densify ceramic materials by utilizing thermal and mechanical energy, resulting in high-density ITO ceramic targets with densities ranging from 91% to 96%. The process involves heating a mold, adding samples and setting the mold on a heating plate, while controlling the melting temperature and time.", "sections": [], "updated_at": "2026-10-16" }