Surface engineering for new industrial applications - bio application

Transcription

1 Surface engineering for new industrial applications - bio application Dr. Yangchun Dong Bsc. Msc. PhD Tel.: Mobile: /10/2013, Brno

2 Introduction 1. A few questions to answer: What is Surface Engineering? Why is surface engineering an solution to some industrial problems? What are common surface engineering technologies? 2. Potential solution to the current biomaterial surface problems. 3. Characterisation methods used for material after surface treatment. 2

3 Surface engineering social and economical impacts Estimated 1% GNP of UK industrialisation can be saved via tribology improvement according to UK Financial Study In USA, 5.3% can be saved according to US Tribology Study 1977 & For combustion engine, around 40% energy is used to compensate the friction losses. Surface corrosion in the USA cost staggering $274 billion nationwide, which is approximately 3.1% of the GDP. Hospital-acquired Infections(HAIs) 3

4 Principal surface engineering technologies Thermal hardening Surface Modification Thermochemical Mechanical Working base Energy beam Surface coating Chemical Thermal spraying Welding PVD CVD base 4

5 Development of biomaterials Developing a new biomaterial can be costly and time consuming. Materials design & research In vitro evaluation In vivo tests Clinical studies Final products Materials selection In vitro tests Animals tests Materials modification Cells & proteins Large animal tests Structural analysis Bacteria Property evaluation A shorter route is to use existing biomaterials and modify/change the selected surface properties to achieve particular target based on the application of the material required. 5

6 Targeted properties of biomaterials Many properties on the surface of biomaterials can be modified by above techniques to achieve maximum performance: Chemical composition Fracture toughness Topography Abrasion resistance Non mechanical properties Wetability & Surface Energy Mechanical Properties Friction factor Biocompatibility & Material strength Cytotoxicity Corrosion resistance Hardness It is worth noting that some properties of materials are not independent and sometimes change one of the factor means compromising of the others. 6

7 Surface engineering of biomaterials A number of ways can be used to create enhanced properties on the surface of biomaterials: i.) Coat the biomaterial surface with an additional layer of thin film which possess properties that the substrate material doesn t have; ii.) Modify the surface properties of material in order to enhanced the property; iii.) Modify the surface material or to achieve additional property; iii.) Add the desired property directly into the processing of manufacture; iv.) combine of i.) ii.) and iii.) 7

8 Wear Factor (mm 3 m -1 N -1 ) Some of the current surface engineering of biomaterials Titanium counterface modification reducing wear of UHMWPE 1.00E E E-07 Severe abrasive Adhesive wear 1.00E-08 against Ti6Al4V against treated Ti6Al4V 1.00E-09 PE/Ti PE/TOed Ti 8

9 Some of the current surface engineering of biomaterials Titanium oxide barrier coating for the heart stents material Ni + TiNi Ni % TiNi Shape memory alloy TiO 2 TiNi TiNi 3 3 9

10 Some of the current surface engineering of biomaterials Multilayer surface engineering of antibacterial stainless steels Technology: Paraequilibrium Plasma Surface Alloying Material surface properties: Wear resistance; Fatigue resistance; Surface hardness; Load bearing capacity; Corrosion resistance; Anti-bacterial properties. Resulting in long lasting, more reliable components. Patent Pending 10

11 Some of the current surface engineering of biomaterials Multilayer surface engineering of Co-Cr alloy for reducing the metal ion-release from prosthesis material surface PLUS Technology: Dimple+ Paraequilibrium Plasma Surface Alloying Material surface properties: Abrasion resistance; Fatigue resistance; Surface hardness; Corrosion resistance; Ion-release; Resulting in long lasting and safe prosthesis material Wear of texturing surface after rolling test 11

12 Depassivation of chromium oxide layer Diffusion controlled Process: N + and/or C + active species bombard the surface, which removed the oxide layer 12

13 Advanced characterisation methods Characterisation methods for analysing material surface can be simple as well as complicated: Tribology test Different wear tests Microstructure Phases analysis Morphological analysis Elemental distribution profile High-resolution crystallography analysis X-ray Diffraction SEM, AFM, Confocal EDS, WDS, GDOES FIB TEM Properties Corrosion resistance Bonding strength Antibacterial Immersion Electrochemical test Peeling test Scratch test Biocompatibility 13

14 Advanced characterisation methods - FIB TEM Nano particles g -M4N M=Cu, Fe, Cr Expanded f.c.c. 2 um Depth increase 14

15 Advanced characterisation methods Post-wear x-section morphology EBSD 15

16 Conclusion remarks Surface engineering has wide application in industry sectors including energy, automotive, aerospace, medical, consumer products etc. Surface engineering for biomaterial is needed to meet the demand of the fast growing market of biomaterial especially in developing countries. Raised concern of the potential cytoxicity from the released ions of metal-on-metal devices is asking for an effective and simple solution. Various surface modification processes have been developed to enhance hardness and wear properties of stainless steels such as PVD coating, plasma nitriding and carburizing process. Combined surface texturing and surface hardening might be the right solution for improving the wear and friction properties of bearing couples in order to minimizing the need for early revisional surgery. 16