1. Excellent Heat Resistance: After curing, phenolic resin forms a three-dimensional cross-linked structure with a high decomposition temperature (typically 150-200°C for long-term use, and over 260°C for short-term use). It resists deformation or decomposition at high temperatures, making it suitable for high-temperature environments.
2. Good Electrical Insulation: Phenolic resin itself is an excellent insulating material (volume resistivity ≥ 10¹²Ω·cm), and the cotton fibers are tightly bonded to the resin, eliminating any conductive pathways. Therefore, it is suitable for electrical insulation applications.
3. High Mechanical Strength: The cotton fiber structure enhances the material's tensile, impact, and flexural properties (tensile strength typically ≥ 80 MPa, flexural strength ≥ 100 MPa), surpassing those of pure resin products.
4. Chemical Resistance: Phenolic resin is resistant to acids (such as hydrochloric acid and dilute sulfuric acid), oils (mineral oil and transformer oil), and organic solvents (such as ethanol and acetone), but is susceptible to corrosion by strong oxidizing acids (such as concentrated nitric acid).
5. Dimensional Stability: After curing, it exhibits low shrinkage and is not susceptible to water absorption (water absorption ≤ 0.5%). It exhibits minimal dimensional change under temperature and humidity fluctuations, making it suitable for precision components.
6. Self-extinguishing and flame retardant properties: Phenolic resin is inherently flame-retardant and produces very low smoke during combustion, meeting most fire protection requirements without the need for additional flame retardant treatment.
Key Advantages of cotton phenolic bar
Based on the above characteristics, phenolic cotton cloth rods offer the following advantages in practical applications:
• Durability: Heat-resistant, corrosion-resistant, and aging-resistant, they offer a long service life and reduce maintenance costs.
• Safety: Insulating and flame-retardant, they are suitable for safety-critical applications (such as electrical equipment and rail transit).
• Processing Flexibility: After curing, they exhibit moderate hardness and can be formed into complex shapes through conventional machining (cutting, drilling, and turning).
• Cost Affordability: The raw materials (cotton cloth and phenolic resin) are relatively inexpensive, and the manufacturing process is mature, resulting in a lower overall cost than high-performance engineering plastics (such as polyimide) or ceramics.
Processing Methods
The processing of phenolic cotton cloth rods requires selecting the appropriate process based on their post-curing hardness (semi-hard to hard). Common steps include:
1. Cutting and Cutting to Length:
The raw rod (typically 8-280mm in diameter) is cut to the required length using a saw or pipe cutter.
2. Surface Treatment:
• Polishing: Use sandpaper or a polisher to remove burrs and improve surface smoothness.
• Drilling/Tapping: Use a high-speed steel drill or carbide tool to create mounting holes. The speed should be controlled to avoid heat generation and delamination.
• Plating/Coating: Electroplating with nickel or chromium (to enhance conductivity and wear resistance) or spraying with epoxy resin (to enhance corrosion resistance) are available upon request.
3. Precision Machining:
For high-precision dimensional requirements (such as for electrodes and precision molds), CNC lathes or milling machines can be used for turning, slotting, and other operations. Cooling steps should be added during processing to reduce frictional heat.
Main Application Areas
Phenolic cotton cloth rods, with their combined advantages of heat resistance, insulation, and mechanical strength, are widely used in the following applications:
1. Electrical and Electronics Industry
• Insulating components: winding bobbins, insulating sleeves, and high-voltage insulating pull rods in motors and transformers; insulating partitions and supports in high-voltage switchgear.
• Electronic Equipment: relay bases, coil bobbins, and printed circuit board (PCB) fixtures (requires heat and moisture resistance).
2. Machinery and Industrial Equipment
• Wear-resistant structural parts: bearing retainers, gears (for low-speed, heavy-load applications), and scrapers in conveying equipment (oil and corrosion resistant).
• Mold accessories: positioning blocks and backing plates for injection and stamping molds (high-temperature resistant and easy to process).
3. Rail Transit and Aerospace
• Rail Vehicles: traction converter insulation supports and pantograph insulators for subways and high-speed trains (vibration and corona resistant). • Aviation components: Non-load-bearing structural parts that require heat resistance (such as fixed brackets in equipment compartments).
4. Chemical and Energy
• Corrosion-resistant vessels: Agitator sleeves in reactor linings, pipeline valve gaskets (acid and alkali resistant).
• Oil production: Insulated centralizers for pumping units (oil and high/low temperature resistant).
Summary
Phenolic cotton cloth is a functional composite material with outstanding cost-effectiveness, making it irreplaceable in applications requiring a balance of heat resistance, insulation, and mechanical strength. While polyimide and polytetrafluoroethylene may be substituted for these materials in applications requiring high temperatures (>300°C) or ultra-high frequencies (such as microwave environments), its comprehensive performance and cost advantages ensure its widespread use in mid- and low-end industrial applications.
