Titanium Oxide Surface Layer for Bone Repair Materials
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Solution Overview
Problem
Existing bioactive bone repair materials face issues with ion elution, poor apatite-forming ability, scratch resistance, and uneven surface formation, which affect their bonding with living bone and durability.
Innovation Solution
A titanium oxide surface layer with positively charged irregularities, formed through alkali or sandblasting treatments, followed by acidic aqueous solution treatments, which enhances apatite formation and scratch resistance while minimizing ion elution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a titanate layer is formed on titanium surface to enable apatite formation, then apatite-forming ability is improved, but sodium ions and calcium ions are eluted from the surface, disturbing the surrounding body fluid environment
Solution Approach 1:
The invention changes the chemical composition parameter of the surface layer from titanate (which contains sodium and calcium) to titanium oxide (which does not contain these ions). This parameter change eliminates ion elution while maintaining apatite-forming ability, as titanium oxide surfaces can still promote apatite formation through different mechanisms such as surface charge and chemistry without releasing harmful ions into the body fluid.
2Strength
If titanium oxide layer is formed by treating with water or acidic aqueous solution, then scratch resistance is improved, but apatite-forming ability becomes poor
Solution Approach 1:
The invention optimizes the surface treatment parameters by using alkali treatment instead of water or acidic aqueous solution treatment. This parameter change in the treatment method maintains both scratch resistance and apatite-forming ability, as alkali treatment creates a surface morphology and chemistry that promotes apatite formation while providing mechanical durability.
Solution Approach 2:
The invention uses alkali treatment as an intermediary process that mediates between the conflicting requirements of scratch resistance and apatite-forming ability. The alkali treatment creates an intermediate surface state that satisfies both requirements, unlike direct water or acidic treatment which compromises one property for the other.
3Ease of manufacture
If hydrogen peroxide treatment is applied to improve surface properties, then cleaning ability is improved, but scratch resistance becomes low
Solution Approach 1:
The invention changes the chemical agent used for surface treatment from hydrogen peroxide (which degrades the surface) to alkali treatment (which strengthens the surface). This parameter change in the treatment chemistry provides both effective cleaning and enhanced scratch resistance, as alkali treatment creates a more durable surface morphology compared to oxidative degradation.
4Reliability
If anodic oxidation is used to form surface layer, then apatite-forming ability is improved, but deep holes are formed unevenly making sterilization difficult
Solution Approach 1:
The invention changes the surface treatment method from anodic oxidation (which creates uneven deep holes) to alkali treatment (which creates uniform surface irregularities). This parameter change in the treatment mechanism achieves both apatite-forming ability and surface uniformity, as alkali treatment produces consistent surface morphology throughout the sample, facilitating uniform sterilization.
5Strength
If surface treatment is performed to create irregularities for bonding, then bonding ability is improved, but surface uniformity becomes poor
Solution Approach 1:
The invention optimizes the surface treatment parameters by controlling alkali treatment conditions (concentration, temperature, time) to achieve uniform surface irregularities. This parameter optimization ensures that the surface uniformity is maintained at the macro level while creating necessary micro-irregularities for bonding, resolving the contradiction between bonding ability and surface uniformity.
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 solution provides a bioactive bone repair material with improved apatite-forming ability, high scratch resistance, and uniform surface characteristics, ensuring reliable bonding with living bone and reduced risk of surface peeling.
Implementation Method 1
the surface layer causes phosphate ions and calcium ions to be adsorbed in this order
Implementation Method 2
the surface layer is positively charged under an aqueous solution environment... the surface layer causes phosphate ions and calcium ions to be adsorbed
Implementation Method 3
heating the washed and dried surface of the titanium substrate and the surface of the titanium alloy in an atmosphere of oxygen or air at a temperature of 500°C to 700°C
Implementation Method 4
a first surface treatment process of treating the surface of titanium and titanium alloy using a mixed solution of hydrofluoric acid and nitric acid
Data Source
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Figure 6~7
AI summary
Bone repair materials are disclosed, from which ions are hardly eluted in living body and which are superior in apatite-forming ability and resistance to apatite peeling and have a scratch resistance high enough for practical use. The material comprises a substrate made of titanium or titanium alloys, and a surface layer, made substantially of titanium oxide, along the surface of the substrate. The substrate has on the surface thereof irregularities of from 1 nm to 10 µm in average in both width and depth. The layer has a zeta potential of +4.5 mV or more under an aqueous solution environment of pH 6 to 8, and a critical scratch resistance of 35 mN or more when vibration 100 µm in amplitude is added to a stylus with a spring constant of 200 g/mm on the surface layer and the stylus is moved at a rate of 10 mm/sec under a load increasing at a rate of 100 mN/min.