Calcium-Deficient Silicate-Substituted Apatite for High-Temperature Stability
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Solution Overview
Problem
Existing calcium phosphate materials used for bone repair and coatings on medical devices lack thermal stability and osteoinductivity, particularly when exposed to high temperatures, leading to phase decomposition and reduced effectiveness in applications requiring sintering above 1100°C or thermal spraying.
Innovation Solution
Development of calcium-deficient silicate-substituted apatite compositions with specific Ca/P and Ca/(P+Si) molar ratios, achieved by treating silicate-substituted calcium phosphate apatite materials with acidic solutions, which enhances thermal stability and maintains osteoinductive properties even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calcium phosphate materials are used for bone repair and coatings, then osteoinductive properties are achieved, but thermal stability deteriorates at high temperatures above 1100°C
Solution Approach 1:
The patent modifies the chemical composition parameters of calcium phosphate materials by controlling the Ca/P molar ratio to fall within 1.5-2.0 and incorporating silicate substitutions. These parameter changes enable the material to maintain both osteoinductive properties and thermal stability up to 1300°C, resolving the contradiction between biological activity and heat resistance.
Solution Approach 2:
The patent creates a composite calcium phosphate-silicate material system where silicate ions are incorporated into the hydroxyapatite structure. This composite approach enhances thermal stability while preserving osteoinductive properties, allowing the material to withstand high temperatures during sintering and thermal spraying processes.
2Strength
If calcium phosphate materials are subjected to high temperature sintering above 1100°C, then structural density is improved, but phase decomposition occurs
Solution Approach 1:
The patent adjusts the chemical composition by controlling Ca/P molar ratio (1.5-2.0) and incorporating silicate substitutions, which raises the phase decomposition temperature to above 1300°C. This enables high-temperature sintering to achieve structural density without phase decomposition, as the modified composition remains stable at these temperatures.
3Strength
If thermal spraying is performed at high temperatures, then coating adhesion is improved, but material melting and impurity phase formation occur
Solution Approach 1:
The patent modifies the material composition with controlled Ca/P ratios and silicate incorporation, which elevates the melting point and thermal stability to above 1300°C. This allows thermal spraying at high temperatures to achieve strong coating adhesion without material melting or formation of impurity phases, as the composition remains stable under these conditions.
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 resulting calcium-deficient silicate-substituted apatite compositions exhibit improved thermal stability and osteoinductive properties, enabling their use in manufacturing macroporous ceramic bone graft substitutes and coatings for medical devices without phase change at high temperatures, thus accelerating bone repair.
Implementation Method 1
treating silicate-substituted calcium phosphate apatite materials with acidic solutions
Implementation Method 2
exhibit improved thermal stability and osteoinductive properties, enabling their use in manufacturing macroporous ceramic bone graft substitutes and coatings for medical devices without phase change at high temperatures
Data Source
AI summary
A calcium-deficient silicate-substituted calcium phosphate apatite composition comprises an apatite phase having a Ca/P molar ratio of from greater than 2.15 to 2.30, and a Ca/(P+Si) molar ratio of from 1.45 to 1.55. A method of producing a calcium-deficient silicate-substituted calcium phosphate apatite composition comprises contacting a silicate-substituted calcium phosphate apatite starting material with an acidic solution to produce the calcium-deficient silicate-substituted calcium phosphate apatite composition. The starting material comprises an apatite phase and up to 15 wt % total of a phase or phases other than the apatite phase, and has a Ca/P molar ratio of from 2.3 to 2.6, and a Ca/(P+Si) molar ratio of from 1.56 to 1.66, and the calcium-deficient silicate-substituted calcium phosphate apatite composition comprises an apatite phase having a Ca/P molar ratio lower than the Ca/P ratio of the starting material apatite phase.