Composite Abrasive Tool Porosity Control
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Solution Overview
Problem
There is a need for improved abrasive tools with high porosity to achieve precise grinding and polishing of hard and brittle materials like silicon carbide wafers, as existing tools struggle to produce ultra-fine surface finishes and maintain effective grit distribution without oxidation issues.
Innovation Solution
A composite abrasive tool is developed with a metal bond and abrasive grains, where the metal bond includes a nickel-tin-bronze system with controlled porosity, achieved through the use of bronze to reduce oxidation and enhance sinterability, and the incorporation of hollow glass spheres or leachable dispersoids to create interconnected and closed pores, allowing for high porosity and effective grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional metal bonds are used for abrasive tools, then structural strength is maintained, but oxidation occurs and porosity control is insufficient for ultra-fine surface finishes
Solution Approach 1:
The invention changes the chemical composition parameters of the metal bond by incorporating bronze (copper-tin alloy) along with nickel and iron powders. This compositional modification creates a bond that is resistant to oxidation while maintaining structural integrity, enabling the abrasive tool to achieve ultra-fine surface finishes without degradation from oxidation.
Solution Approach 2:
The invention uses a composite metal bond system comprising multiple metal powders (nickel, iron, bronze) in specific proportions. This composite approach combines the beneficial properties of each metal: nickel provides strength and oxidation resistance, iron contributes to sinterability, and bronze enhances porosity control. The composite material achieves properties that individual metals cannot provide alone.
2Productivity
If high porosity is introduced into the abrasive tool, then grinding efficiency and coolant access improve, but structural strength may be compromised
Solution Approach 1:
The invention intentionally creates a porous structure within the metal bond by controlling the particle size distribution and packing of metal powders, and by incorporating bronze that facilitates pore formation. This porous structure allows coolant penetration and chip evacuation while the intermetallic bonding and sintering process maintain sufficient structural strength for tool integrity during grinding operations.
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 composite abrasive tool achieves surface finishes of 500 Angstroms or less, significantly reducing surface roughness and maintaining tool performance by controlling porosity and oxidation, enabling efficient grinding of hard and brittle materials like silicon carbide wafers.
Implementation Method 1
a metal bond and abrasive grains, where the metal bond includes a nickel-tin-bronze system with controlled porosity, achieved through the use of bronze to reduce oxidation and enhance sinterability
Implementation Method 2
Pores of an abrasive tool typically provide access to grinding fluids, such as coolants and lubricants
Data Source
Figure 1a~1b
Figure 1c
Figure 2a~2b
AI summary
Abrasive articles possessing a highly open (porous) structure and uniform abrasive grit distribution are disclosed. The abrasive articles are fabricated using a metal matrix and the open structure is controlled with a porosity scheme, including interconnected porosity (e.g., formed by leaching dispersoid), closed porosity (e.g., induced by adding hollow micro-spheres and/or sacrificial pore-forming additives), and/or intrinsic porosity (e.g., controlled via matrix component selection to provide desired densification). In some cases, manufacturing process temperatures for achieving near full density of metal bond with fillers and abrasives are below the melting point of the filler used, although sacrificial fillers may be used as well. The abrasive articles are useful in high performance cutting and grinding operations, such as back-grinding silicon, alumina titanium carbide, and silicon carbide wafers to very fine surface finish values. Techniques of use and manufacture are also disclosed.