Silicon carbide ceramic structural components

How are silicon carbide ceramic structural components processed?

Today, as industrial manufacturing continues to move towards high precision and sophistication, silicon carbide ceramic structural components are widely used in semiconductor equipment, aerospace, chemical equipment and other fields due to their excellent wear resistance, high-temperature stability and outstanding mechanical strength. However, the extremely high hardness of silicon carbide also brings a problem: it is difficult to process. So, how are silicon carbide ceramic structural components processed? The editor of Heheng New Materials Technology will focus on this issue and provide a detailed analysis of its processing flow, technical difficulties and advanced solutions.

I. Why are silicon carbide ceramic structural components difficult to process?

Silicon carbide (SiC) is a covalently bonded ceramic material with a Mohs hardness as high as 9.2, second only to diamond. This high hardness enables it to perform well in harsh environments, but it also poses challenges during the processing. For example:

The extremely low plastic deformation capacity makes it almost impossible to adopt traditional metal cutting methods.

Cracks and chipping are prone to occur during processing.

The processing efficiency is low and the processing tools are prone to wear and tear.

Precision processing of silicon carbide ceramics requires the use of specialized abrasives and equipment.

Ii. Main Processing Technology flow of Silicon Carbide Ceramic Structural Components

1. Blank forming

Processing begins with raw materials. Silicon carbide blanks are usually manufactured by the following forming methods:

Dry pressing forming: It is suitable for structural components with simple geometric shapes and high requirements for dimensional stability.

Grouting molding or isostatic pressing molding: Suitable for complex structural components, with more uniform density distribution;

Hot-pressing sintering or reaction sintering: It enhances the structural density and is a commonly used method in the customization of silicon carbide ceramic structural components.

2. High-temperature sintering

The sintering temperature is usually around 2000℃ and is classified according to different processes as:

Reaction-sintered silicon carbide (RBSiC) : It forms a dense structure through the reaction of liquid silicon and is suitable for large-sized components.

Hot-pressed sintered silicon carbide (HPSiC) : It has a denser structure and better mechanical properties, making it suitable for applications with high strength requirements.

3. Primary mechanical processing (before sintering

To reduce the processing difficulty after sintering, some structures are cut, drilled or turned in the "green body" (unsintered state). This method has relatively low requirements for equipment and moderate processing accuracy, but the size will change due to sintering shrinkage.

Iii. Analysis of Precision Machining Technology After Sintering

The hardness of sintered silicon carbide ceramic structural components is extremely high, and processing can only rely on the CNC processing technology of silicon carbide ceramics, including the following methods:

1. Diamond grinding wheel grinding

Grinding is the most commonly used post-processing method. The surface after sintering is roughly ground and finely ground with a diamond grinding wheel, and the thickness, tolerance and flatness are controlled.

Advantages: Suitable for processing flat surfaces, outer circles and inner holes;

Disadvantages: The processing efficiency is relatively low and it is prone to micro-cracks.

2. Ultrasonic processing

Ultrasonic-assisted grinding can increase the material removal rate and reduce processing damage, making it particularly suitable for high-precision inner hole or complex structure processing.

Suitable scenarios: High-risk areas such as microstructures and thin-walled parts;

When used in combination: brazing diamond tools or ceramic grinding rods.

3. Laser cutting and engraving

Laser can be used for slotting, marking and micro-hole processing in the customization of silicon carbide ceramic structural components. Although there is a heat-affected zone, good quality can be achieved through reasonable parameter optimization.

4. CNC precision machining center

In recent years, with the popularization of high-end equipment, the adoption of silicon carbide ceramic CNC processing technology has become mainstream. Five-axis CNC machines combined with diamond tools can achieve three-dimensional forming of complex curved surfaces, significantly enhancing processing efficiency and consistency.

Iv. Key Points for Quality Control in the Processing of Silicon Carbide Ceramic Structural Components

To obtain high-quality silicon carbide structural components, the following dimensions must be strictly controlled:

Geometric dimension accuracy: Generally, it needs to be controlled within ±0.01mm, and some microstructures have higher requirements.

Surface roughness: RA≤0.2μm is a typical requirement for high-end equipment.

Internal stress elimination: During the processing, it is necessary to prevent hot cracks and residual stress concentration.

Microcrack-free structure: Non-destructive testing techniques (such as ultrasonic and X-ray) are adopted to ensure consistent quality.

V. Typical Application Scenarios and Processing Requirements

Semiconductor equipment components, such as burners, wafer clamps, and carriers, need to achieve high dimensional stability and low particle release.

Wear-resistant parts for aero engines: They need to have high strength and heat shock resistance.

Precision industrial fluid components: such as sealing rings and nozzles, require extremely high sealing performance and flatness;

Laser and optical platform support components: It is necessary to control micro-deformation and high-precision flatness.

The editor of Heheng New Materials Technology concludes: The processing of silicon carbide ceramic structural components is not "invincible"

Although the processing of silicon carbide ceramic structural components is highly challenging, through mature precision silicon carbide ceramic processing technology, the support of CNC machine tools, the combination of diamond tools and the cooperation of experienced operators, it is entirely possible to achieve high-precision and large-scale stable output.