Razor Blade Coating with Chromium Boride for Hardness and Durability
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Solution Overview
Problem
Razor blades face a trade-off between increased hardness and brittleness due to hard coatings, leading to reduced durability, and existing deposition methods require larger chambers and longer times for depositing dissimilar materials.
Innovation Solution
A razor blade with a hard coating layer composed of nanocrystalline chromium boride dispersed in an amorphous chromium-boron mixture, formed using a single composite target under controlled sputtering conditions, enhancing adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the hardness of the coating thin-film is increased, then the strength of the razor blade edge is improved, but the brittleness increases and durability deteriorates
Solution Approach 1:
The patent applies composite materials by combining multiple coating layers with different properties: a hard coating layer (Cr, CrB, Cr2B) for hardness, an intermediate layer (Mo, W) to reduce brittleness and improve adhesion, and a polymer coating (PTFE) for low friction. This multi-layer composite structure resolves the contradiction by distributing functions across different materials, achieving both high strength and durability.
Solution Approach 2:
The patent introduces an intermediate layer composed of molybdenum or tungsten between the hard coating layer and the blade substrate. This intermediary layer serves as a buffer that reduces the brittleness of the hard coating while improving adhesion to the substrate, thereby preventing coating delamination and enhancing overall durability without sacrificing edge strength.
2Manufacturing precision
If dissimilar materials are deposited by arranging two or more sputter targets, then the deposition quality is improved, but the chamber size and deposition time increase
Solution Approach 1:
The patent merges multiple sputter targets into a single composite target containing Cr, CrB, and Cr2B phases. This single target can simultaneously deposit all necessary hard coating materials in one deposition process, eliminating the need for multiple targets and sequential deposition steps, thereby reducing both chamber size requirements and total deposition time while maintaining coating quality.
Solution Approach 2:
The single composite target serves multiple functions by containing different crystalline phases (Cr, CrB, Cr2B) that can deposit various coating materials with different properties. This multi-functional target replaces what would traditionally require multiple specialized targets, streamlining the deposition process and reducing manufacturing complexity.
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 hard coating layer improves the razor blade's strength and durability by balancing hardness and brittleness, while the single composite target deposition method reduces processing time and chamber size.
Implementation Method 1
forming a hard coating layer by performing physical vapor deposition (PVD) on the heat-treated blade substrate, on which the blade edge is formed, by using a single composite target
Implementation Method 2
a method has been proposed to perform deposition under a single sputtering condition with a single sputter target in which dissimilar materials are mechanically bonded together
Data Source
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AI summary
The present disclosure provides an improvement to razor blade coating by a physical vapor deposition method, by forming a hard coating layer as a thin coating layer in which chromium boride, which is a nanocrystalline structure having high hardness, is dispersed in an amorphous mixture of chromium and boron, thereby improving the strength and hardness of the thin coating layer and securing the bonding force by chromium in the amorphous mixture between the hard coating layer and a blade substrate on which an edge of the razor blade is formed.