Cutting Insert Soldering with Copper Tungsten Double Layers
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Solution Overview
Problem
Polycrystalline diamond cutting inserts for hard and tough materials face challenges in soldering or welding due to the thermal instability of cobalt-containing matrices, which decompose at temperatures above 750 °C, making it difficult to join hard metals effectively.
Innovation Solution
A cutting insert with a sintered hard metal carrier and cutting plate, using a solder with a sequence of double layers of copper-based and tungsten-based layers, along with an intermediate layer of silver, copper, or nickel alloy, allowing for brazing below 750 °C by ensuring sufficient wetting and reaction kinetics, and optionally a titanium or tungsten-based cover layer for enhanced bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional soldering or welding is used to join hard metals, then strong connections are achieved, but the cobalt-containing matrix decomposes at temperatures above 750 °C
Solution Approach 1:
A multi-layer intermediate structure is introduced between the hard metal and the solder, consisting of a copper-based layer and a tungsten-based layer arranged in sequence. This intermediate structure enables effective joining at temperatures below 750°C by facilitating thermal and metallurgical compatibility, preventing direct thermal damage to the cobalt-containing matrix while maintaining strong joint strength
Solution Approach 2:
The solder system employs a composite multi-layer structure combining copper-based and tungsten-based layers. The copper-based layer provides good wetting and bonding characteristics, while the tungsten-based layer offers high temperature stability and prevents interdiffusion. This composite approach enables successful brazing below 750°C with sufficient joint strength
2Stability of the object's composition
If the temperature is kept below 750 °C to protect the cobalt matrix, then material stability is maintained, but soldering becomes difficult due to insufficient reaction kinetics
Solution Approach 1:
The invention changes the physical and chemical parameters of the solder system by introducing a multi-layer structure with specific thickness ratios and material compositions. The copper-based layer is designed with optimized thickness to ensure rapid wetting and bonding at lower temperatures, while the tungsten-based layer provides thermal stability. These parameter optimizations enable sufficient reaction kinetics below 750°C without compromising matrix stability
Solution Approach 2:
The copper-based intermediate layer acts as a mediator that enhances wetting and bonding reactions at temperatures below 750°C. This intermediate structure facilitates the soldering process by providing a pathway for controlled diffusion and reaction, overcoming the kinetic limitations that would otherwise prevent effective joining at low temperatures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables effective joining of hard metals at temperatures below 750 °C, achieving strong soldered connections with high shear strength, suitable for processing hard materials like rock and reinforced mineral building materials.
Implementation Method 1
The solder achieves sufficient wetting of the carbide at a temperature below 750 °C in order to join the insert to the carrier
Implementation Method 2
enables the brazing of hard metals below 750°C
Implementation Method 3
The sequence of copper and tungsten ensures fast reaction kinetics and a lowering of the melting temperature of the copper and enables the brazing of hard metals below 750°C
Data Source
Figure 1~2
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Figure 5~6
AI summary
A cutting insert 12 for a rotating tool has a carrier 24 made of sintered carbide and a cutting plate 22, which has a base body 25 made of sintered carbide and polycrystalline diamond 21 on a cutting surface 18 of the base body. A solder 26 bonds the base body 25 of the cutting plate 22 to the carrier 24, wherein the solder 26 has a sequence 27 of double layers (26) each consisting of a copper-based layer 29 and a tungsten-based layer 30, and the number of double layers 28 is greater than twenty.