钎焊工艺

这是一篇关于钎焊工艺的思维导图，介绍了焊接过程中的加热速率、钎焊温度、钎焊时间以及冷却速率等关键参数。还提到了钎焊过程在受控环境中进行，以确保焊缝表面的高质量。特别指出了液态填充物的高表面张力，这有助于形成良好的焊缝。主要概述了一个详细的钎焊工艺流程，包括接头设计、材料准备、焊接参数、环境控制以及设备使用等方面。

Furnace Brazing Process

• 1. Basic introduction
  • Key Focus
    • Joint design
    • Material to be joined
    • Filler metal/钎料
    • Flux/钎剂
    • Heating methods
    • Joint preparation
• 2. Brazing Process
  • Process control parameter
    • Cleaned parts and brazing filler metal are assembled
    • Heating rate
    • Brazing temperature
    • Brazing Time
    • Cooling Rate
    • Carried out in a controlled atmosphere
      • Inert
      • Vacuum
  • Appraisal element
    • Filler metal flow
      • High surface tension of liquid filler metal
      • Low contact angle
      • Low viscosity
    • Base metal characteristics
    • Filler metal characteristics
    • Surface preparation
    • Joint design and clearance
    • Temperature and time
    • Rate and source of heating
    • Protection by an atmosphere of flux
• 3. Furnace & Control Instrumentation
  • High-temperature nickel-base alloys brazing
    • 1095 ℃
    • Uniformity: ±8℃
  • Aluminum alloys
    • Uniformity: ±3℃
  • Thus it is vital that each work load be closely monitored with a minimum of two thermocouples attached to or embedded in the parts to be brazed.
  • An alarm system can be installed in the microprocessor to detect any operational abnormality that has the potential to terminate the brazing operation.
  • Furnace type
    • Continuous
    • Semi-continuous
    • Batch
      • • An alarm system can be installed in the microprocessor to detect any operational abnormality that has the potential to terminate the brazing operation.
• 4. Advantage
  • Variables easily controlled to ensure the reliability, brazing atmosphere can be easily regulated
  • When brazing procedures established, relatively unskilled operators can carry out;
  • The absence of flux entrapment allows more flexibility in joint design. The postbraze cleaning of the brazed part and the furnace are unnecessary;
  • Because a whole assembly is heated, distortion of the part can be minimized or eliminated. In some cases, heat treatment of the part can be incorporated into the brazing cycle.
  • More than one joint per work piece can be brazed in a brazing cycle. Several different assemblies requiring the same brazing conditions can also be brazed simultaneously.
• 5. Process limitations
  • Initial investment is relatively high and equipment maintenance is also critical; The cost of a special atmosphere must also be considered.
  • Because the whole assembly is heated, the cost of heating exceeds that of other brazing operations. In addition, microstructural changes in the base metal can be occured, depending on the material being brazed and the brazing temperature.
  • Because brazing is performed inside the furnace, joint design is important. The fixtures for holding a brazed assembly require extral heat mass, which increase the manufacturing cost. Proper joint design can minimize or even eliminate fixture complexity.