Al2O3-TiC Ceramic Sinter for Magnetic Head Substrate Machinability

Solution Overview

Problem

Current ceramic sintered bodies for magnetic heads, such as Al2O3--TiC-based sintered bodies and compound ceramic materials, face challenges in achieving high machinability and smoothness for low-flying magnetic heads, leading to issues with grain fall-off and poor polishing efficiency, which hinder the attainment of high recording densities.

Innovation Solution

A ceramic sintered body comprising Al2O3 crystal grains with internal and external TiC crystal grains, where the external TiC grains contact the Al2O3 grains, optimizing the area proportion, grain size, and lattice constant to enhance machinability and electrical conductivity, while maintaining mechanical strength and reducing fracture toughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If Al2O3—TiC-based sintered bodies are used for magnetic head substrates, then mechanical strength is improved, but machinability deteriorates and grain fall-off occurs

Engineering Contradiction:

Improvemechanical strengthVSAvoidmachinability

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent applies local quality by creating a dual-phase microstructure where Al2O3 crystal grains provide mechanical strength while TiC crystal grains specifically enhance machinability. The TiC grains are distributed within and between Al2O3 grains, creating localized regions with different properties: Al2O3 regions maintain structural integrity while TiC regions facilitate controlled cracking during machining, thereby improving machinability without compromising overall mechanical strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining Al2O3 and TiC crystal grains in a specific microstructural arrangement. This composite structure leverages the high strength properties of Al2O3 and the machinability-enhancing properties of TiC, creating a material that simultaneously achieves both mechanical strength and improved machinability, resolving the contradiction between these two properties.

Inventive Principle:

Principle #40Composite materials

2Reliability

If fracture toughness is increased to prevent grain fall-off, then reliability is improved, but machining efficiency deteriorates

Engineering Contradiction:

Improvegrain fall-off resistanceVSAvoidmachining efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by creating a dual-phase microstructure where Al2O3 crystal grains provide mechanical strength while TiC crystal grains specifically enhance machinability. The TiC grains are distributed within and between Al2O3 grains, creating localized regions with different properties: Al2O3 regions maintain structural integrity while TiC regions facilitate controlled cracking during machining, thereby improving machinability without compromising overall mechanical strength.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses parameter changes by controlling the size, distribution, and orientation of TiC crystal grains within the Al2O3 matrix. By adjusting parameters such as TiC grain size (0.1-10 μm), TiC content (1-50 wt%), and sintering temperature (1000-1700°C), the material achieves optimal balance between fracture toughness and machinability, enabling efficient machining while preventing grain fall-off.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If surface smoothness is improved for low-flying magnetic heads, then recording density is improved, but machining complexity increases

Engineering Contradiction:

Improvesurface smoothnessVSAvoidmachining complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses parameter changes by controlling the size, distribution, and orientation of TiC crystal grains within the Al2O3 matrix. By adjusting parameters such as TiC grain size (0.1-10 μm), TiC content (1-50 wt%), and sintering temperature (1000-1700°C), the material achieves optimal balance between fracture toughness and machinability, enabling efficient machining while preventing grain fall-off.

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 ceramic sintered body allows for efficient machining, reduced grain fall-off, and improved surface smoothness, enabling stable floating and high recording densities in magnetic heads, with enhanced electrical conductivity and thermal management.

Implementation Method 1

a ceramic sintered body comprising Al2O3 crystal grains with internal and external TiC crystal grains

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentUS8173281B2Ceramic sinter, magnetic head substrate using the same, magnetic head and recording medium drive unit

Publication Date: 2012.05.08 KYOCERA CORP

AI summary

A ceramic sintered body contains Al2O3 crystal grains, internal TiC crystal grains existing in the Al2O3 crystal grains and external TiC crystal grains other than the internal TiC crystal grains. The Al2O3 crystal grains and the external TiC crystal grains retain stress caused by the difference in thermal expansion coefficient remaining after sintering, so that the Al2O3 crystal grains and the external TiC crystal grains pull each other in the interface therebetween. As a result, when the ceramic sintered body is machined, micro-cracks generated in the interface can easily grow due to the residual stress in addition to the shearing force caused by the machining operation, so that machinability is improved.