Ferrite-Coated Abrasive Particles for Post-Sintering Magnetism

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Solution Overview

Problem

Existing methods for creating magnetically responsive abrasive particles face challenges such as high-temperature oxidation of magnetic materials during the sintering process, leading to loss of magnetic properties, and the need for additional coating steps that can result in agglomeration and uneven coatings.

Innovation Solution

The development of magnetizable abrasive particles with a ferrite coating applied before sintering, which remains responsive to magnetic fields after high-temperature processing, and the use of a method that allows for a single-sided or uniform coating of ceramic particles within a mold, preventing agglomeration and ensuring even orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic materials are applied to abrasive particles after sintering, then magnetic properties are preserved, but additional coating steps are required which cause agglomeration and uneven coatings

Engineering Contradiction:

Improvemagnetic propertiesVSAvoidcoating steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The magnetic material is applied to the abrasive particle surface before sintering, allowing the magnetic coating to be formed simultaneously with the ceramic matrix densification. This preliminary action eliminates the need for separate post-sintering coating steps and prevents agglomeration issues that would arise from handling coated particles after sintering.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The sintering process and magnetic coating formation process are merged into a single operation. By applying the magnetic material precursor before sintering, the thermal processing that densifies the ceramic matrix also sinteres the magnetic coating, combining two separate processes into one and simplifying the overall manufacturing procedure.

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If magnetic materials are applied before sintering, then manufacturing steps are reduced, but high-temperature oxidation during sintering may loss magnetic properties

Engineering Contradiction:

Improvemanufacturing stepsVSAvoidmagnetic properties

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The sintering process is conducted in a controlled atmosphere that prevents oxidation of the magnetic material. By creating an inert or reducing environment during high-temperature processing, the magnetic properties of the coating are preserved while still achieving densification of the ceramic matrix.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

A composite structure is formed where the magnetic material is integrated with the ceramic matrix during sintering. The resulting composite maintains the magnetic properties of the coating material while benefiting from the mechanical strength and stability of the sintered ceramic structure.

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If multiple coating steps are used to ensure uniform coating, then coating evenness is improved, but manufacturing time and complexity increase

Engineering Contradiction:

Improvecoating evennessVSAvoidmanufacturing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The coating application and sintering processes are continuous and integrated. The magnetic material precursor is applied to the green body surface, and the subsequent sintering process continuously densifies both the matrix and coating in a single thermal cycle, eliminating the need for multiple separate coating and drying steps.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The sintering parameters (temperature, atmosphere, time) are optimized to achieve uniform magnetic coating formation. By controlling the thermal history and chemical environment during sintering, uniform densification and magnetic property development are achieved in a single process step.

Inventive Principle:

Principle #35Parameter changes

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 ferrite-coated abrasive particles maintain magnetic properties post-sintering, reducing manufacturing steps and agglomeration issues, while allowing for precise orientation and improved abrading efficiency in abrasive articles.

Implementation Method 1

a magnetic coating layer applied to the outer surface of the ceramic particle prior to sintering

Methodology Applied

Scientific EffectSintering: Sintering

Implementation Method 2

The sintered magnetizable particle is responsive to a magnetic field

Methodology Applied

Scientific EffectMagnetism: Magnetism

Data Source

PatentUS11926782B2Magnetizable abrasive particle and method of making the same

Publication Date: 2024.03.12 3M INNOVATIVE PROPERTIES CO

AI summary

A magnetizable abrasive particle is presented. The magnetizable abrasive particle has a ceramic particle having an outer surface. The magnetizable abrasive particle also has a magnetic coating layer applied to the outer surface of the ceramic particle prior to sintering. The sintered magnetizable particle is responsive to a magnetic field.