CBN Super-Hard Article Paste Sintering for Dimensional Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for efficient methods to produce composite articles with super-hard structures, particularly for use in machine tools and wear-resistant components, as existing methods face challenges in material migration and achieving precise dimensional tolerances.
Innovation Solution
A method involving the combination of raw material powder with an organic binder in a liquid medium to form a paste with a controlled shear rate, which is then extruded onto a substrate and subjected to heat treatment and high pressure to sinter the super-hard structure, minimizing binder residue and preserving the arrangement of raw material grains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional sintering methods are used to make super-hard articles, then the super-hard structure can be formed on the substrate, but material migration occurs between the applied material mixture and substrate, compromising dimensional accuracy
Solution Approach 1:
A paste composition is used as an intermediary material between the substrate and the super-hard structure. The paste contains binder material and has specific rheological properties (shear rate between 1-25 s⁻¹) that prevent material migration during sintering. The binder material acts as a mediator that holds the raw material powder in place, preventing unwanted migration between the applied material and substrate while allowing complete bonding after sintering.
Solution Approach 2:
The invention controls the rheological parameters of the paste, specifically maintaining a shear rate between 1-25 inverse seconds. This parameter control ensures the paste has appropriate viscosity and flow characteristics that prevent material migration during application and sintering, while still allowing complete densification to achieve dimensional accuracy.
2Ease of manufacture
If high binder content is used in the paste to ensure proper extrusion and bonding, then the paste can be easily formed and applied, but excessive binder residue remains after heat treatment, affecting the purity of the super-hard structure
Solution Approach 1:
The binder content is optimized to a specific range (5-20 mass percent) and the paste is formulated with controlled rheological properties (shear rate 1-25 s⁻¹). This parameter optimization ensures sufficient binder to enable proper extrusion and bonding, while limiting the amount that remains as residue after heat treatment, thus balancing ease of manufacture with purity requirements.
3Loss of substance
If the raw material powder content is increased to reduce binder residue, then the purity of the super-hard structure improves, but the paste becomes too viscous to extrude and apply properly
Solution Approach 1:
The paste composition is optimized with raw material powder content between 80-95 mass percent and binder content between 5-20 mass percent, with specific control of shear rate (1-25 s⁻¹). This parameter optimization allows high powder content for purity while maintaining sufficient fluidity for extrusion by adjusting the binder properties and their interaction with the powder.
Solution Approach 2:
The invention replaces reliance on high binder content for paste formation with controlled rheological parameters (shear rate control). This substitution allows the paste to maintain extrudability through controlled flow properties rather than excessive binder, enabling high powder content while preserving ease of manufacture.
4Ease of manufacture
If conventional paste composition is used with high binder content, then the paste can be easily applied, but the arrangement of raw material grains is disrupted during sintering, reducing manufacturing precision
Solution Approach 1:
The binder material acts as an intermediary that maintains the arrangement of raw material grains during sintering. The controlled paste composition and rheological properties ensure that grains remain in their original positions while the binder provides necessary adhesion, preventing grain rearrangement and preserving manufacturing precision.
5Manufacturing precision
If the sintering process is extended to ensure complete transformation of raw material powder, then the super-hard structure density improves, but the processing time increases, reducing productivity
Solution Approach 1:
The paste is pre-formed with optimized composition and rheological properties (shear rate 1-25 s⁻¹) before sintering. This preliminary preparation ensures uniform distribution of raw material powder and binder, creating a homogeneous structure that sinters more uniformly and completely in less time, thus improving both density tolerance and productivity.
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 results in super-hard articles with improved dimensional accuracy, reduced processing requirements, and enhanced reliability, achieving tighter shape and density tolerances, while minimizing material rearrangement and oxide impurity deposition.
Implementation Method 1
The paste assembly is heat treated to remove the binder material and provide a pre-sinter assembly
Implementation Method 2
The pre-sinter assembly is subjected to a pressure and temperature sufficient to sinter the raw material powder and transform it into the super-hard structure bonded to the substrate
Data Source
AI summary
This application describes a method of making a super-hard article that includes a super-hard structure bonded to a substrate. The super-hard structure generally includes a sintered plurality of super-hard grains made from cubic boron nitride. The method generally includes providing raw material powder suitable for sintering the super-hard structure; combining the raw material powder with an organic binder material in a liquid medium to form a paste; providing a substrate assembly having a formation surface area configured for forming a boundary of the super-hard structure, the substrate having a recess coterminous with the formation surface area; extruding the paste into contact with the formation surface area to provide a paste assembly; and heat treating and/or sintering the paste assembly to remove the binder material and provide a pre-sinter assembly.