Ultra-Hard Hardfacing Inserts for Brazing and Resistance Welding
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Solution Overview
Problem
The adhesion of thermally stable polycrystalline diamond and polycrystalline cubic boron nitride hard facing inserts to substrates is limited due to low wetting of molten braze materials, making it difficult to attach these ultra-hard materials to a high proportion of the surface effectively.
Innovation Solution
The use of an ultra-hard body insert with a welding node and wire configuration, where the wire traverses the body's surface and is coated with a boundary layer to enhance wettability, allowing for resistance welding and subsequent brazing, ensuring strong attachment to the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermally stable polycrystalline diamond inserts are used for hard facing, then wear resistance is improved, but adhesion to braze material deteriorates due to low wetting
Solution Approach 1:
A boundary coating layer is introduced as an intermediary between the ultra-hard body and the braze material. This coating layer has high wettability with the braze material, enabling effective adhesion while preserving the wear resistance of the underlying diamond or cubic boron nitride body.
Solution Approach 2:
The insert structure becomes composite, combining the ultra-hard body material (diamond or cubic boron nitride) with a boundary coating layer having different properties. The coating layer provides chemical compatibility with the braze material, while the core body maintains extreme hardness and wear resistance.
2Ease of manufacture
If wire is wrapped around the body to provide electrical connection, then welding capability is improved, but device complexity increases
Solution Approach 1:
The wire serves multiple functions simultaneously: it provides electrical connection for resistance welding, acts as a mechanical retaining element, and creates a predetermined gap structure. This multi-functionality reduces the need for separate components, offsetting the added complexity with functional consolidation.
Solution Approach 2:
The electrical connection path is segmented into discrete wire portions that can be independently positioned and adjusted. The wire is arranged in specific configurations (wrapped around the body) to create distinct functional zones for welding and gap control.
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
This method provides a robust and efficient attachment of ultra-hard bodies to the substrate, allowing for a high proportion of surface coverage with minimal gaps, improving wear resistance and reducing tool wear during grinding.
Implementation Method 1
a boundary coating on the ultra-hard body for rendering the body wettable by a braze material
Implementation Method 2
resistance welding the or each TSP insert to the substrate by applying electrical current to the welding node
Implementation Method 3
the weld produced by the melted wire causes a predetermined gap to be present between the substrate and the ultra-hard body, which gap may be filled by capillary action in the subsequent brazing step
Data Source
AI summary
The present invention relates to inserts for hard facing substrates, and a method for hard facing substrates. An insert according to an embodiment of the present invention may comprise a body of ultra-hard material having a welding node located on a first surface thereof and at least one wire electrically connecting the first surface to a second, opposite, surface. In use, the inserts may be temporarily connected to a substrate by applying a resistance welding electrode to the welding node, thereby causing the wires on the second surface to melt and weld the insert to the substrate. A subsequent brazing step may firmly attach the inserts to the substrate.