Detailed explanation of professional knowledge in ceramic insulation materials industry

According to the national standard GB/T 8411.1-2008, ceramic insulation material is defined as an inorganic material formed before sintering. Its main composition usually contains polycrystalline silicate, aluminosilicate and simple or complex oxides (such as ferrite). This definition also includes certain non-oxide materials, such as aluminum nitride. Ceramic insulation materials are divided into nine groups (indicated by the character "C" as the head) according to their composition and performance. Alumina ceramics are the most widely used type. They are made of high-purity alumina (Al₂O₃) as the main component. They have extremely high volume resistivity (up to 4.5×10¹⁵Ω·m at room temperature and low field strength) and excellent mechanical strength. For Ceramic Body for Siemens, the ceramic body used in Siemens electrical systems is usually made of 95% or 99% alumina ceramics to ensure long-term reliability in harsh industrial environments. Nitride ceramics (such as aluminum nitride, hexagonal boron nitride) have both high insulation and high thermal conductivity, and are suitable for heat dissipation substrates of electronic components. Composite ceramics obtain optimized comprehensive properties through doping modification, which can improve thermal shock resistance while maintaining high insulation. In the field of fuses, Ceramic Body for Mersen, which is used in Mersen fuses, is usually made of Steatite or alumina ceramics. The specific requirements depend on the voltage level, breaking capacity and installation environment of the fuse.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The performance characteristics of ceramic insulation materials are usually comprehensively evaluated through three dimensions: electrical, mechanical and thermal. In terms of electrical performance, volume resistivity is the core indicator. The volume resistivity of high-quality ceramic insulation materials at room temperature can reach 10¹⁴ to 10¹⁵Ω·cm and remains stable throughout the entire operating temperature range. Studies have shown that in the temperature range from -50°C to 150°C, the volume resistivity fluctuation amplitude of ceramic insulating materials is much smaller than that of organic insulating materials, which is attributed to the stability of its grain boundary carrier migration paths. The ability to resist charge accumulation is a key performance in high-voltage DC applications. The charge density on the surface of ceramic materials can be reduced by more than 50% compared with traditional epoxy materials. This feature is particularly important for the ceramic body of DC fuses, because surface charge accumulation may cause electric field distortion and trigger surface flashover. In terms of mechanical properties, ceramic insulation materials have extremely high compressive strength.

 

Some advanced ceramics can reach 1400MPa, which is several times or even dozens of times that of conventional epoxy materials. In addition to electrical insulation properties, Ceramic Body for Auto Fuses also needs to withstand vibrations, temperature cycles and possible salt spray corrosion in the engine compartment. Ceramic materials perform significantly better than plastic-based insulation materials in these harsh environments. In terms of corrosion resistance, ceramics have excellent resistance to most acids, alkali and salt solutions, and the corrosion rate in hydrofluoric acid environments is much lower than that of epoxy materials. Regarding Ceramic Body for Fast Fuses, since fast fuses are usually used to protect sensitive electronic equipment, the ceramic body also needs to have good dimensional stability and a low thermal expansion coefficient to ensure that the installation size of the fuse does not drift after multiple on-off cycles.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The manufacturing process of ceramic insulators (including the ceramic body of the fuse) is a multi-step precision process. Step 1: Powder preparation - Weigh high-purity alumina, talc, clay and other raw materials according to the formula, add grinding aids and dispersants, and perform wet grinding through ball milling or stirring mill to obtain a slurry with uniform particle size distribution. For the Steatite Ceramic HRC Fuse Body, which is a high-breaking capacity fuse ceramic body made of talc porcelain, the proportion of talc (the main component is hydrated magnesium silicate) in the raw material is relatively high, which makes the talc porcelain have good processability and a moderate dielectric constant. The ground slurry needs to be subjected to iron removal treatment to remove magnetic impurities that may reduce the insulation performance, and then passed through a spray drying tower to produce granulated powder with good fluidity. Step 2: Forming - Fill the granulated powder into the mold, and obtain the green body through dry pressing, isostatic pressing or slip molding. For the Din Type Steatite Ceramic HRC Fuse Body, that is, the DIN standard talc porcelain high-breaking fuse ceramic body, because it needs to comply with the installation dimensions and interchangeability requirements of international standards, the accuracy of the molding mold must be controlled at a high level to ensure that the dimensional tolerance after sintering meets the requirements of IEC or DIN standards. Step 3: Sintering - the green body goes through three stages of pre-sintering, high-temperature sintering and cooling in a high-temperature kiln.

 

The sintering temperature varies depending on the material: alumina ceramics usually need to be sintered above 1600°C, while talc porcelain has a lower sintering temperature, about 1300°C. During the sintering process, diffusion and rearrangement occur between ceramic particles, the porosity is significantly reduced, the material reaches densification, and the final mechanical strength and electrical properties are obtained at the same time. Step 4: Precision processing - For ceramic insulators that require strict dimensional tolerances or complex shapes, mechanical processing such as grinding, drilling or cutting is required after sintering. The dimensional accuracy of ±0.01mm can be achieved using CNC machine tools, which is particularly important for the ceramic body of the micro fuse. For Alumina Ceramic Insulator for NH/Blade Type Fuses, that is, alumina ceramic insulator for NH blade type fuses, the mounting groove and the mating surface of the blade contact need to be precision ground to ensure reliable contact with the metal contacts. Step 5: Inspection and packaging - Conduct appearance inspection, dimensional measurement, breakdown voltage test and volume resistivity sampling inspection on the finished product. Qualified products are delivered in shock-proof packaging.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The quality of the fuse ceramic body is often reflected in the microscopic details that are visible or perceptible to the naked eye. The first is the surface and edge condition of the inner cavity - the inner cavity of a high-quality ceramic body should have a uniform sintering luster, no sand, and no exposed pores, because any surface defects in the inner cavity may become anchor points for arc stagnation, directly affecting the breaking performance. For Ceramic Body for DC Fuse Link, the DC arc burning time is longer and the requirements for inner cavity surface quality are more stringent. At the edge, it is necessary to observe whether the ridge line is continuous and straight, and whether there is a jagged chip. Even a small edge chip may gradually expand and cause structural failure in a vibration environment. The second is dimensional consistency and wall thickness uniformity - the batch dimensional stability of Ceramic Body for Auto Fuses directly determines the consistency of the melt loading position, which in turn affects the repeatability of the fusing characteristics. Place the ceramic body under strong light for transmission observation. Products with uniform wall thickness should have the same degree of light transmission; local excessive light transmission often means that the wall thickness is thin or the density is insufficient, which may become an area of ​​concentrated thermal stress when breaking large currents. For high-breaking applications such as Steatite Ceramic HRC Fuse Body, wall thickness uniformity is the basic prerequisite to ensure that the shell does not burst.

 

In addition, for products such as Din Type Steatite Ceramic HRC Fuse Body and Alumina Ceramic Insulator for NH/Blade Type Fuses that need to be mated with metal contacts or bases, the matching accuracy of the mounting grooves and positioning features is also worthy of focus. Use standard gauges or actual mating parts for trial assembly. Qualified products should be inserted smoothly without obvious shaking. Another detail that is easily overlooked is the amount of deformation after sintering - place the ceramic body flat on a datum surface and observe whether there is warping or distortion. Even a slight amount of bending can cause the melt to deviate from the center position after assembly or cause uneven gaps in the arc-quenching sand filling.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

We provide one-stop OEM services for Electrical Insulators of Ceramic Material from raw material ratio, mold design, dry pressing molding, high temperature sintering to precision grinding. Our engineering team can quickly complete the design of the ceramic body solution based on your rated voltage, breaking capacity and installation interface requirements. Welcome to submit drawings or technical specifications for process evaluation and sample docking.