Hydroxyapatite Coated Titanium Substrate
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Solution Overview
Problem
Existing methods for coating hydroxyapatite on titanium-based metal substrates are time-consuming and require multiple steps, and the resulting coatings often have low surface hardness, making them unsuitable for applications requiring strength and osteoblast proliferation.
Innovation Solution
A method involving surface roughening of titanium-based metal substrates, adhering hydroxyapatite powder, and sintering at controlled temperatures and atmospheres to achieve a robust hydroxyapatite coating with high hardness, suitable for osteoblast proliferation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet method using simulated body fluid is used to prepare hydroxyapatite coating on metal substrate, then hydroxyapatite coating can be obtained, but the number of steps is high and production time is long (several days or more)
Solution Approach 1:
The patent replaces the chemical wet method with a mechanical sputtering deposition method. The sputtering apparatus uses physical sputtering to deposit hydroxyapatite coating on the metal substrate, eliminating the need for multiple chemical immersion steps in simulated body fluid. This mechanical/physical approach reduces production time from several days to a single step process while maintaining coating quality.
Solution Approach 2:
The patent changes the deposition parameters by controlling the sputtering power, gas flow rate, and deposition time to achieve optimal hydroxyapatite coating. By adjusting these parameters, the method achieves high-quality coating formation in a single step without requiring multiple immersion cycles, thus improving productivity while maintaining reliability.
2Strength
If hydroxyapatite is sintered by hot pressing, then compressive strength of 200 MPa or more is achieved, but bending strength and impact strength are low and the material is easily broken
Solution Approach 1:
The patent creates a composite structure by coating metal substrate (titanium or stainless steel) with hydroxyapatite layer. The metal substrate provides high bending strength and impact strength, while the hydroxyapatite coating provides compressive strength and bone affinity. This composite structure combines the advantages of both materials, achieving overall excellent mechanical performance that neither material could achieve alone.
Solution Approach 2:
The patent applies different material properties to different parts of the implant structure. The metal substrate core provides mechanical strength and toughness, while the hydroxyapatite surface layer provides compressive strength and osteoconductivity. This local differentiation of material properties allows the implant to meet diverse mechanical requirements in different regions.
3Reliability
If titanium is used for artificial organs, then excellent corrosion resistance and bone compatibility are achieved, but it is easily worn and mold processing is more difficult than stainless steel
Solution Approach 1:
The patent separates the functional requirements into two parts: the metal substrate handles mechanical strength and wear resistance, while the hydroxyapatite coating handles corrosion resistance and bone compatibility. This segmentation allows optimization of each material for its specific function, and the coating process can be applied to various metal substrates regardless of their processing characteristics.
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 method reduces the number of steps and time required for hydroxyapatite coating while achieving a high-hardness layer that supports osteoblast proliferation, suitable for medical applications such as artificial bones and joints.
Implementation Method 1
a sputtering method, wherein a hydroxyapatite coating is formed on a metal substrate by sputtering
Implementation Method 2
ions produced by an ion source
Data Source
Figure 1
Figure 2~2(d)
Figure 3~4
AI summary
In the present invention, a titanium-based metal substrate formed from pure titanium or a titanium alloy is subjected to a surface roughening treatment such that that surface roughness Ra thereof reaches 1.6-4.0 µm, HAp powder is adhered to the entire surface or a part of the surface of the surface-roughened titanium-based metal substrate at a prescribed ratio, and the HAp powder is sintered to the surface of the metal substrate by retaining the titanium-based metal substrate, to which the HAp powder has been adhered, at a prescribed sintering temperature for 3-11 hours in an atmospheric, nitrogen gas, argon gas, oxygen gas or carbon dioxide gas atmosphere.