Porous Orthopaedic Implant Bonding via Intermediate Layer
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Solution Overview
Problem
Existing methods for manufacturing orthopaedic implants with porous surfaces face challenges in maintaining the integrity of the porous structure and bonding it to substrates without degrading the mechanical properties, particularly for complex geometries and materials like titanium alloy Ti6Al4V, where sintering and traditional diffusion bonding can cause deformation and rapid degradation of fatigue properties.
Innovation Solution
The method involves creating a porous layer and an intermediate layer, bonding them using cold isostatic pressing and vacuum welding, followed by a diffusion bond created through hot isostatic pressing, which allows for the attachment of porous structures to substrates with complex geometries without compromising the mechanical properties or porosity, using titanium or titanium alloys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sintering is used to bond porous layer to substrate, then bonding is achieved, but porous structure deforms and porosity is compromised
Solution Approach 1:
The patent introduces an intermediate layer between the porous layer and substrate. This intermediate layer serves as a mediator that can be bonded to both the porous layer and substrate without requiring high-temperature sintering that would deform the porous structure. The intermediate layer enables bonding while protecting the porous structure's integrity and porosity.
2Strength
If traditional diffusion bonding is used to bond layers, then bonding is achieved, but complex geometries cannot be accommodated due to uniaxial force requirements
Solution Approach 1:
The intermediate layer enables the use of isostatic pressing instead of uniaxial diffusion bonding. Isostatic pressing applies pressure uniformly from all directions, which can accommodate complex geometries without requiring complex fixturing. The intermediate layer facilitates this bonding approach while maintaining the integrity of the porous structure.
3Strength
If mechanical pressure is applied during sintering to hold porous structure and substrate in contact, then bonding is achieved, but porous structure is deformed and distorted
Solution Approach 1:
The intermediate layer acts as a buffer that protects the porous structure from direct mechanical pressure during bonding. By bonding to the intermediate layer rather than directly to the porous layer, the substrate can be secured without applying deforming pressure to the porous structure, thus maintaining its shape and porosity.
4Strength
If sinter bonding is used for Ti6Al4V substrate, then bonding is achieved, but beta grain size increases and fatigue properties degrade
Solution Approach 1:
The intermediate layer enables bonding of Ti6Al4V substrate without requiring sinter bonding temperatures that cause beta grain growth. By using the intermediate layer as a bonding interface, the substrate can be bonded at lower temperatures or through alternative mechanisms that do not trigger phase transformations, thus preserving the fatigue properties of the Ti6Al4V substrate.
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
This approach ensures reliable and economical bonding of porous layers to substrates with complex geometries, maintaining the porosity and mechanical integrity of the orthopaedic implants, enabling effective tissue ingrowth and improved fatigue properties.
Implementation Method 1
bonding the porous layer to the intermediate layer
Implementation Method 2
bonding the porous layer to the intermediate layer, providing a solid substrate in the form of an orthopedic implant device, and bonding the intermediate layer to the solid substrate
Implementation Method 3
a diffusion bond created through hot isostatic pressing
Implementation Method 4
a diffusion bond created through hot isostatic pressing
Data Source
AI summary
A method of manufacturing an orthopaedic implant device having a porous outer surface is described. In one embodiment, the implant device includes a porous layer, an intermediate layer, and a solid substrate. The porous layer is preferably bonded to the intermediate layer by cold isostatic pressing. The intermediate layer is preferably bonded by vacuum welding to the solid substrate such that the porous layer forms at least a portion of the outer surface of the orthopaedic implant device. Preferably, a diffusion bond is created between the bonded intermediate layer and the solid substrate by hot isostatic pressing. In another embodiment, a porous layer is created on an outer surface of a solid layer by selective melting. Preferably, the solid layer is bonded to the solid substrate such that the porous layer forms at least a portion of the outer surface of the orthopaedic implant device.