Surface Modification Of Titanium Alloy Research Articles

Strategies For Immobilization Of Bioactive Organic Molecules On Titanium Implant Surfaces – A Review

Numerous approaches have been used to improve the tissue-implant interface of titanium (Ti) and titanium alloy (Ti6Al4V). They all aim at increasing cell migration and attachment to the metal, preventing unspecific protein adsorption and improving post-implantation healing process. Promising methods for titanium and titanium alloy surface modification are based on the immobilization of biologically active organic molecules. New and interesting biochemical approaches to such surface modification include layer-by-layer deposition of polyelectrolyte films, phage display-selected surface binding peptides and self-assembled DNA monolayer systems. The present review summarizes the scientific information about these methods, which are at in vitro or in vivo development stages, and hopes to promote their future application in dental implantology and in oral and maxillofacial surgery.

Reciprocating Sliding Wear Performance of Hard Coating on Modified Titanium Alloy Surfaces

The high strength, low weight, and outstanding corrosion resistance properties possessed by titanium alloys have led to a wide range of successful applications in aerospace, automotive, and chemical industries and in power generation. Titanium alloys are characterized by poor wear resistance properties and their utilization has been excessive in nontribological applications. Surface texturing is a well-known and effective means of surface modification to improve the tribological properties of sliding surfaces. In the present work, modification of titanium alloy surfaces (Ti6Al4V) was done by lapping and laser surface texturing. The wear-resistant coating, AlCrN, was applied over the modified titanium alloy surfaces, with and without a chromium interlayer. Linear reciprocating sliding wear tests were performed with ball-on-flat contact geometry to evaluate the tribological performance of the coated alloy. The tests were performed under different normal loads for a period of 105 cycles at a frequency of 5 Hz. The friction force between the contact pair and displacement of the ball were simultaneously observed using a force transducer and laser displacement sensor. Optical microscopy was used to quantify the wear volume by measuring the wear scar diameter on both the specimen and the counterbody. Scanning electron microscopy (SEM) was employed to study the morphology of the wear scar. The characteristic behavior of the AlCrN coating such as bonding strength, wear volume, wear rate, and coefficient of friction with the chromium interlayer was evaluated and compared with the coating directly applied over the substrate. The coating on the textured surface, with the chromium interlayer showed better tribological performance.

Tribological improvement of titanium alloy surfaces through texturing and TiAlN coating

Titanium alloys are characterised by poor wear resistance properties and its utilisation has been excessive in non-tribological applications. Surface texturing is a renowned and effective means of surface modification technique to improve the tribological properties of sliding surfaces. In the present work, modification of titanium alloy surfaces was done by lapping and laser surface texturing. The modified surfaces were coated by titanium aluminium nitride (TiAlN) nanocomposite coating with chromium as interlayer by cathodic arc physical vapour deposition system. The adhesion characteristics of the coatings were evaluated using a scratch tester and recognised that coating adherence has been improved by 8% through texturing. The effect of normal load on friction and wear characteristics were examined and discussed. The present work is aimed for investigating the bonding strength, friction coefficient and wear behaviour of bilayer composite coating over modified titanium alloy substrates under dry sliding contact condition.

Surface Modification of Titanium Alloys Using Alumina Particles Blasting for Biomedical Applications

Ti-based bulk metallic glass (BMG) is a new class of titanium alloys that exhibits excellent properties for biomedical applications. They have high strength, good corrosion resistance, low elastic modulus and satisfactory biocompatibility. Therefore, Ti-based BMG is an excellent alternative material to be used in biomedical application. Titanium alloy with a nominal composition of the Ti40Zr10Co36Pd14 was synthesized by replacing Cu with Co in a better-known bulk glass forming composition. Coin-shape samples with a diameter of 15 mm and thickness of 1 mm were prepared by arc-melting and casting into copper mold. The coin-shape samples were polished, then followed by blasting with 50 μm and 250 μm average particle sizes of alumina. Alumina blasting caused plastic deformation at the surface and induced change in surface roughness. The larger size of alumina particle, the higher the Ra, Rq and Rt with significant difference. Some abrasive alumina particles were found to be embedded onto the blasted surface. The blasted Ti40Zr10Co36Pd14 sample showed lower roughness values than those blasted Ti-6Al-4V samples. This may be because of the higher hardness values of Ti40Zr10Co36Pd14 sample, when compared to the softer Ti-6Al-4V samples. The contact angle measurement which demonstrated wettability of all samples did not show significant difference in a tested range of Ra (from 40 to 428 nm).

Enhanced adhesive strength between shape memory polymer nanocomposite and titanium alloy

Abstract Due to their unique shape memory capability, shape memory materials have been studied in numerous areas that require shape reconfiguration. This capability enables the adaptive wing structural concept. The structure prototype required enhanced interfacial strength between the shape memory polymer composite and structural metal alloys to enable the use of the shape memory polymer composite in this application. The interfacial adhesion properties between the shape memory polymer composite and a titanium alloy were systematically investigated. Surface modification of the titanium alloy with silane coupling agents improved the adhesion strength. The shape memory polymer was toughened using amphiphilic poly(n-butylene oxide)-b-poly(ethylene oxide) and with carbon nanotubes. The toughened shape memory polymer composite showed enhanced adhesion strength compared to the non-toughened system. Toughened shape memory polymer with both 5 wt% poly(n-butylene oxide)-b-poly(ethylene oxide) and 2 wt% carbon nanotube against surface-modified titanium alloy showed up to 113.5% increase in the adhesion strength, compared to the control. To investigate the adhesion mechanism, the adhesive fracture surface was investigated by tracking the locus of failure using high-resolution electron microscopy and energy dispersive X-ray spectroscopy.

Surface performance of nanoscale particles and amorphous reinforced laser alloying coatings

The laser alloying (LA) metal–ceramics coatings usually show a general wear resistance. To improve this condition, the nanoscale particles (NP) and amorphous reinforced LA coating was researched. The synthesis of a hard coating on a TA7 titanium alloy by laser alloying (LA) of Stellite12–Zn-B4C mixed powders was investigated by means of scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM). The novel aspect of the proposed system is that lot of the nanorods and the amorphous phases are found to be produced in such LA coating, and the nanoscale CoZn13 phase is appeared at the intersplat region, and its lattice value is very compatible to its d-space at the orientation of (221). Compared with a TA7 alloy substrate, an improvement of the wear resistance was observed for such LA composite coating. This study provides the theoretical and experimental to promote the application of LA technique in surface modifications of titanium alloys.

Titanium alloy surface modification by excimer laser irradiation

Abstract The main effects of the interaction of UV emitting KrCl (at 222 nm) and XeCl (at 308 nm) excimer lasers with titanium alloy Ti6Al4V are presented. Single-pulse and multi-pulse irradiations were used, with varying laser beam fluences. The resulting interactions with the surface show thermal character, and produce: (i) damages in the form of craters at higher pulse counts and fluences of 7 J cm−2 and 7.2 J cm−2, which are far above the damage threshold; (ii) melt pools with visible wave-like structures at periphery; (iii) resolidified droplets and cracks at periphery (at higher pulse count), (iv) increasing content of oxygen, with a domination of TiO2.

Studies on the Bioceramic Coating on Titamium Substrate Including Silicon and Calcium by Micro-Arc Oxidation and Osteoblast’s Adhesion and Proliferation on the Coating

This study used micro-arc oxidation technology for pure titanium alloy surface modification, which 400μm titanium beads were sintered into porous titanium in vacuum conditions, and produced silicon and calcium coatings. Scanning electron microscope(SEM), X-ray diffraction (XRD) and Energy dispersion spectrometer(EDS) were employed to investigate the surface morphology and phase composition of the coatings. The results are listed as follows: the main component of porous titanium MAO coating is anatase TiO2,and the coating introduced silicon and calcium element successfully. The proliferation ability of osteoblasts on the oxidized and unoxidized surface was determined by CCK-8 method, The results indicated that both the proliferation and adhesion ability of osteoblast on the oxidized surface were better than the unoxidized surface.

In vitro evaluation of H2O2 hydrothermal treatment of aged titanium surface to enhance biofunctional activity

Surface modification of titanium has been extensively investigated in implant science and technology in an effort to improve its osteoconductivity. The rate of protein adsorption on titanium surfaces is known to vary depending on the chemistry, structure, morphology, and titanium-specific biological aging of the surface. It is thus desirable to modify smooth titanium surfaces of miniimplants used as orthodontic anchors immediately prior to use. In this study, we have developed a simple surface modification of titanium alloy that improves its biofunctional activity. The surface of a Ti-6Al-4V disk was modified by applying 3% H(2)O(2) hydrothermal treatment using an autoclave. A nanostructured porous network TiO(2) was observed on the treated surface. Treated surfaces exhibited higher hydrophilicity, protein adsorption, and cell proliferation than untreated surfaces. 3% H(2)O(2) hydrothermal treatment is thought to provide biofunctional activity for aged titanium surface.

Surface modification of titanium alloy with laser synthesised ceramics reinforced composite coating

The synthesis of the hard composite coating reinforced with TiB2–TiC on titanium alloy using laser surface engineering has been investigated in detail. A composite coating with metallurgical joint to the substrate was formed. This composite coating mainly consisted of γ-(Fe, Ni), Fe3Al, Al3Ti, TiC, TiB2, Cr7C3 and TiNi. Microstructure of this composite coating revealed microsized blocky precipitates and submicrometre sized sperical precipitates. Compared with the titanium alloy substrate, an improvement of the microhardness and the wear resistance was obtained for this composite coating.

Bio-tribological properties of UHMWPE against surface modified titanium alloy

In order to improve the tribological properties of UHMWPE sliding against Ti6Al4V alloy, three different methods were applied to modified the alloys surface, namely two-step plasma immersion ion implantation, thermal oxidation (TO) and laser surface texturing (LST). Structure and wettability of surface modified titanium alloy were investigated. Friction and wear properties of UHMWPE sliding against modified alloys were tested by a pin-on-disc tribometer under distilled water and bovine serum respectively. The results showed that a graded titanium oxide–titanium nitride film and a titanium oxide film formed separately after being treated by ion implantation and TO, thus contributing to the improvement of wettability of alloy surfaces. The friction coefficients of modified Ti6Al4V alloys decreased obviously, especially for the TO-treated one, which reached as low as 0.015. The wear rate of UHMWPE was reduced and the lowest wear rate was obtained when sliding against the ion implanted one. Almost no notable wear features presented on the titanium alloy treated by ion implantation.

Effects of anodic oxidation and hydrothermal treatment on surface characteristics and biocompatibility of Ti–30Nb–1Fe–1Hf alloy

Anodic oxidation followed by hydrothermal treatment has been widely applied for surface modification of titanium alloys to precipitate a crystalline hydroxyapatite (HA) layer in order to achieve improved osteoconduction. A majority of the studies in the literature imposed relatively high powers to enhance Ca and P in the anodic oxide film (AOF). However, high powers have been found to cause deterioration of the adhesive strength in one of the author's previous study. In this study, a new electrolyte comprising calcium acetate monohydrate (CA), β-glycerophosphate disodium pentahydrate (β-GP) and HA powder was developed, and the Ti–30Nb–1Fe–1Hf alloy was anodized in this HA-containing electrolyte to a relatively low voltage. Results show that the AOF anodized in the HA-containing electrolyte exhibits a better HA forming ability during hydrothermal treatment, attributing to the presence of HA powder in the electrolyte that effectively enhances both the Ca content and Ca/P ratio in the AOF. On the other hand, the adhesive strength was little affected due to the decrease in size of the craters residing in the AOF. With respect to the biological responses, not much difference in biocompatibility of the treated and untreated Ti–Nb surfaces was obtained. However, the anodized and hydrothermally treated surface promotes the attachment of cells.

Surface modification of titanium alloy with laser cladding RE oxides reinforced Ti3Al–matrix composites

Ti3Al–matrix composites were prepared by laser cladding of the Al3Ti/TiB2/Al2O3 pre-placed powders on the Ti–6Al–4V alloy, which can improve the wear resistance of the substrate. With addition of the proper content of RE oxides (nano-Y2O3), this composite coating exhibited finer microstructure and better wear resistance. Nevertheless, excessive RE oxides could lead to the production of the micro-crack, and also decrease the temperature of the molten pool leading to the present of the un-melted TiB2 block, which can significantly decrease the wear resistance of this composite coating.

Surface modification of titanium alloy with the Ti3Al + TiB2/TiN composite coatings

Laser cladding of the Ti3Al + TiB2 pre‐placed alloy powder on the Ti–6Al–4 V alloy in nitrogen protective atmosphere can form the Ti3Al + TiB2/TiN composite coating, which can dramatically improve the wear resistance of the Ti–6Al–4 V alloy surface. In this study, the Ti3Al + TiB2/TiN composite coatings on the Ti–6Al–4 V alloy have been researched by means of X‐ray diffraction, SEM and energy dispersive spectrometry. It was found that there is a metallurgical combination between the Ti3Al + TiB2/TiN composite coating and the substrate. The microhardness of the Ti3Al + TiB2/TiN composite coatings were 3 ~ 4 times higher than that of the Ti–6Al–4 V alloy because of the actions of the Ti3Al + TiB2/TiN hard phases and the grain refinement strengthening. Moreover, the wear mass losses of the Ti3Al + TiB2/TiN composite coatings were much lower than that of the substrate. Copyright © 2011 John Wiley & Sons, Ltd.

Effects of 3,4-dihydrophenyl groups in water-soluble phospholipid polymer on stable surface modification of titanium alloy

The surface of a titanium (Ti) alloy substrate was modified by a simple and quick process using a water-soluble polymer, and the effects of 3,4-dihydroxyphenyl (DHP) groups in the polymer side chain on the modification process were examined. The polymers (PMDP) composed of both 2-methacryloyloxyethyl phosphorylcholine (MPC) unit and 3,4-dihydroxyphenyl methacrylate unit were synthesized for surface anchoring. The Ti alloy substrate was coated with PMDP using an aqueous solution of the polymer. A PMDP layer with a thickness of 20 nm was formed on the Ti alloy substrate simply by dip coating for 10s without drying. Even when the Ti alloy substrate with PMDP coating was immersed in the aqueous medium for 1 week, no change in the thickness was observed, i.e., the PMDP layer was bound to the surface very stably. Oxidation of the DHP groups reduced the stability of the polymer layer significantly. Thus, the DHP groups play a significant role in achieving stable binding. Protein was adsorbed on the Ti alloy substrate; however, this was not observed for the PMDP-coated Ti alloy substrate. In conclusion, we confirmed the effects of DHP groups in PMDP on the stability of the coating on the Ti alloy substrate. Moreover, we found that surface treatment using PMDP was simple, quick, and reliable, and thus, it has great potential for improving biofouling of Ti alloy substrates used in medical devices.

XPS characterization of surface modified titanium alloys for use as biomaterials

Three different Ti alloys of biomedical interest have been studied by means of X-ray photoelectron spectroscopy (XPS) to determine their surface chemical composition in both as-received condition and after oxidation at 750 °C in air for different times. Compositions of the investigated alloys were, in wt.%, Ti–7Nb–6Al, Ti–13Nb–13Zr and Ti–15Zr–4Nb. XPS analyses showed a behaviour of the Ti–7Nb–6Al alloy different from that of the two TiNbZr alloys, evidencing the role of the chemical composition of the alloys on the oxidation mechanisms. The oxidation process generates an aluminium-oxide rich surface on the Ti–7Nb–6Al, while in the case of the TiNbZr alloys a titanium-oxide rich layer is formed. The effect of the heat treatment on the contribution of the minority elements at the surface is also discussed.

Recent advances in laser surface treatment of titanium alloys

This paper reviews progress over the last five years in the field of laser surface modification of titanium alloys. The authors analyze the effect of new laser technologies and new materials as tools for improving surface properties—specifically, biocompatibility and resistance to wear, corrosion, and high temperatures. The authors discuss the effect of laser processing parameters on the microstructure and compare the results obtained by various researchers. Therefore, an overview of the difficulties involved in the laser processing of titanium is provided with a discussion of future prospects.

Magnetic field controlled single crystal growth and surface modification of titanium alloys exposed for biocompatibility

The aim of this work is growth and characterisation of Ti55Nb45 (wt%) single crystals by floating-zone single crystal growth of intermetallic compounds using two-phase radio-frequency (RF) electromagnetic heating. Thereby, the process and, in particular, the flow field in the molten zone is influenced by additional magnetic fields. The growth of massive intermetallic single crystals is very often unsuccessful due to an unfavourable solid–liquid interface geometry enclosing concave fringes. It is generally known that the crystallization process stability is enhanced if the crystallization interface is convex. For this, a tailored magnetic two-phase stirrer system has been developed, which enables a controlled influence on the melt ranging from intensive inwards to outwards flows. Since Ti is favourably light, strong and biocompatible, it is one of the few materials that naturally match the requirements for implantation in the human body. Therefore, the magnetic system was applied to crystal growth of Ti alloys. The grown crystals were oriented and cut to cubes with the desired crystallographic orientations [100] and [101] normally on a plane. The electron backscatter diffraction (EBSD) technique was applied to clearly determine crystal orientation and to localize grain boundaries. The formation of oxidic nanotubes on Ti surfaces in dependence of the grain orientation was investigated, performed electrochemically by anodic oxidation from fluoride containing electrolyte.

Modification of titanium alloy surfaces for percutaneous implants by covalently attaching laminin

Percutaneous implants require a seal at the skin interface. Laminin (L-332) is a component of the basement membrane, integral to epidermal attachment. To enhance the attachment of keratinocytes onto the surface of titanium alloy (Ti(6)Al(4)V), we attached L-332 onto the surface using silanization (L-332==Ti(6)Al(4)V). Iodinated L-332 was used to investigate protein attachment kinetics. L-332==Ti(6)Al(4)V remained attached after immersion in serum compared with adsorbed L-332. Cells from a keratinocyte line (HaCaT) grown on L-332==Ti(6)Al(4)V were significantly smaller (p < 0.05) with over a 20-fold increase in the number of adhesion plaques compared with nontreated Ti(6)Al(4)V control discs or with adsorbed L-332 surfaces. We have shown that it is possible to augment the surface of Ti(6)Al(4)V with L-332 and that this significantly increases the attachment of keratinocytes.

Superplastic Prosthetic Forming - &lt;i&gt;In Vitro&lt;/i&gt; Response

Steinemann, 1998 [1] reported an observation made several decades earlier in 1951, by Leventhal [2] in which ‘bone reaction was studied by the insertion of up to 80 titanium screws into the femora of rats. At the end of sixteen weeks the screws were so tight that in one specimen the femur was fractured when an attempt was made to remove the screw’. Consequently, the main reasons given for the suitability of titanium for surgical implantation are its strength, its failure to cause tissue reaction, and the fact that bone becomes attached to titanium. Now, we call this attachment osseointegration which is considered to be the direct structural and functional connection between living bone and the surface of a load-bearing artificial implant. However, osseointegration is not considered to be a chemical bond between titanium and bone. Implant materials that actually bond to bone are considered to be bioactive. Materials for clinical use can be classified into three categories: resorbable, bioactive and nearly inert materials. A bioactive material is defined as a material that elicits a specific biological response at the interface of the material, which results in the formation of a bond between the tissue and that material. Whereas specific bioceramics are considered to be bioactive, titanium alloys are not normally considered to be so. However, recent surface modification of titanium alloys provide evidence that titanium alloys can become bioactive after treatment with NaOH and the ensuing development of a titanate gel on the metal surface.