Diamond Bonded Body Hard Layer for Stronger PCD Bonding
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Solution Overview
Problem
Conventional methods for manufacturing bonded polycrystalline diamond bodies (PCDs) often result in low bonded strength between the PCD and the hard substrate, leading to detachment issues when used in tools.
Innovation Solution
Incorporating a hard layer made of cobalt and hard grains with a Vickers hardness of 1100 Hv or more between the PCD and the hard substrate, which absorbs excess cobalt and suppresses abnormal grain growth, thereby reducing residual stress and enhancing bonded strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a mixed powder of diamond powder and binder powder is loaded into a tantalum container and sintered under high temperature and high pressure, then a bonded PCD body is manufactured, but the bonded strength between the PCD and the hard substrate is low
Solution Approach 1:
A cobalt layer is introduced as an intermediate layer between the diamond PCD and the hard substrate (cemented carbide). This intermediate cobalt layer acts as a mediator that improves the bonded strength by providing a transition zone that reduces thermal expansion mismatch and enhances adhesion between the diamond and the substrate during sintering under high temperature and pressure.
2Productivity
If the bonded PCD body is used in a tool to machine a workpiece, then the tool performs cutting operations, but the PCD may detach from the tool due to low bonded strength
Solution Approach 1:
The cobalt intermediate layer serves as a mediator that prevents detachment of the PCD from the tool during cutting operations. It provides a gradient transition in material properties between the diamond PCD and the hard substrate, reducing stress concentration and improving mechanical interlocking, thereby enhancing reliability under operational loads.
Solution Approach 2:
The intermediate cobalt layer allows for controlled parameter changes in thermal expansion coefficient and bonding characteristics across the interface between diamond and hard substrate. This gradient in material parameters reduces thermal and mechanical stresses during sintering and operation, preventing detachment.
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 approach significantly increases the bonded strength of the PCD body, preventing detachment and improving the durability and longevity of tools like diamond bits and other cutting tools.
Implementation Method 1
the hard layer 4 contains cobalt and hard grains made of a carbide, a nitride, or a carbonitride... absorbs excess cobalt and suppresses abnormal grain growth
Implementation Method 2
sintered under high temperature and high pressure
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A bonded diamond body (1) having a high bonded strength is provided. The bonded diamond body (1) includes a sintered polycrystalline diamond body (2), a hard substrate (3), and a hard layer (4) provided between the sintered polycrystalline diamond body (2) and the hard substrate (3), the sintered polycrystalline diamond body (2) containing a diamond grain and a sintering aid, the hard substrate (3) containing tungsten carbide and cobalt, and the hard layer (4) containing cobalt and a hard grain made of a carbide, a nitride, or a carbonitride having a Vickers hardness of 1100 Hv or more.