The sintering process in powder metallurgy exhibits a critical dependence on high temperature conveyor belt . These belts serve as core components of sintering furnaces (especially continuous furnaces), playing a vital role in production efficiency, product quality, and process stability. Below is a detailed analysis of their relationship:

1. Criticality of the Sintering Process

• Powder compacts (green compacts) require heating to high temperatures (typically 70%-90% of the base metal’s melting point) and holding under a protective atmosphere (e.g., hydrogen, nitrogen-hydrogen mixture, dissociated ammonia, or vacuum).
• This process enables metallurgical bonding between powder particles through atomic diffusion and grain boundary migration, achieving densification and enhancing strength and properties.
• Continuous sintering furnaces are preferred for large-scale production due to their high efficiency, large capacity, and low energy consumption.

2. Core Functions of the High-Temperature Conveyor Belt

Within continuous sintering furnaces, high-temperature conveyor belts perform these essential tasks:

• Support and Transportation:
  Transport compacts smoothly and continuously from the furnace inlet (low-temperature zone) through the high-temperature sintering zone to the cooling section and outlet. Vibration or deviation must be avoided to prevent deformation or damage.
• Uniform Heating and Support:
  Ensure compacts are heated uniformly at high temperatures, preventing local overheating or under-sintering. Belts must possess high-temperature stability, resisting softening or deformation under prolonged thermal load.
• Atmosphere Protection Barrier:
  Act as a physical carrier for the protective atmosphere, requiring low outgassing to avoid contaminating the atmosphere or the product (e.g., affecting surface finish or magnetic properties).
• Adaptation to Harsh Conditions:
  Withstand high temperatures (typically 800°C–1400°C), atmosphere corrosion (e.g., carburizing/decarburizing environments), mechanical loads (compact weight + chain tension), and thermal cycling stress.

3. Technical Requirements for High Temperature Conveyor Belts

Given these demanding conditions, conveyor belts must meet the following specifications:

4. Common Types of High-Temperature Conveyor Belts

• Metal Mesh Belts:
  • Materials: Austenitic stainless steel (e.g., 314, 310S), Nickel-based alloys (e.g., Inconel 601, Haynes alloys).
  • Features: Good flexibility, light weight, excellent permeability; suitable for medium-low temperature sintering (≤1150°C) and small/medium-sized parts.
• Metal Plate Link Belts:
  • Structure: Interlocking metal plates connected by pins, driven by side chains.
  • Features: High load capacity, stable operation, long service life; suitable for large/heavy parts and higher temperatures (up to 1400°C).
• Ceramic Belts (Special Applications):
  • Materials: Silicon carbide (SiC), Alumina (Al₂O₃) ceramics.
  • Features: Resistant to extreme temperatures (>1400°C) and corrosion, but brittle and costly; primarily used for cemented carbide sintering.

5. Impact on Powder Metallurgy Production

• Quality Assurance: Stable belts reduce product deformation, cracking, and contamination, ensuring dimensional accuracy and consistent performance.
• Cost Control: High-quality belts offer long lifespans (years), reducing downtime, replacement costs, and scrap losses.
• Process Flexibility: Temperature resistance determines the range of sinterable materials (e.g., stainless/tool steels require 1100°C–1300°C).
• Production Bottleneck: Belt speed directly correlates with furnace throughput, making it a key parameter for design capacity.

6. Extended Applications: Post-Sintering Processes

High-temperature belts are also used in continuous post-sintering processes like heat treatment (e.g., carburizing, quenching) and coating sintering (e.g., steam treatment of ferrous parts), further extending their importance.

Summary

The high-temperature conveyor belt is the core carrier enabling continuous sintering in powder metallurgy. Its performance directly influences:

• ✔ Product yield and consistency
• ✔ Production line efficiency and cost
• ✔ Range of processable materials and technical limits

Selecting and maintaining suitable belts (e.g., proper material selection, regular carbon deposit cleaning, avoiding temperature excursions) is crucial for ensuring efficient, stable, and economical operation of PM production lines.
(Example: In an automotive PM gear factory, a high-performance 310S stainless steel conveyor belt can operate 24/7 for years, enabling stable sintering of millions of parts.)