Modell zur Analyse des knöchernen Anwachsverhaltens auf bioaktiv beschichteten Implantatoberflächen

Model to analyse the bone on‐growth on bioactive coated implant surfaces Especially on the field of bone regeneration, transient and permanent implants are an important method of therapy in the Orthopaedic Surgery. In this context, bioactive surfaces on metallic implants provide an improved contact to the surrounding bone. The goal of our study was to establish an in‐vitro test system to evaluate the on‐growth of bone‐derived cells on different surface coatings. Therefore, we invented a special kind of clamps made of commercially‐pure (c‐p) titanium and blasted with hydroxyapatite particles followed by electrochemically coating with calcium phosphate (BONIT®‐HA, BONIT®). Definite pieces of human cancellous bone were attached to these clamps, inserted onto tissue culture plates and cultivated in DMEM for ten days. Finally, the contact area between human cancellous bone and the implant surface was analyzed and the spreading of osteoblast‐like cells evaluated by scanning electron microscopy (SEM). A well‐spread morphology of bone cells was observed on the implant surfaces coated with calcium phosphate (CaP). In comparison the clamps without CaP coatings showed only a marginal growth of bone cells on the clamp surface. The presented newly in‐vitro test setup using titanium clamps coated with bioactive layers attached to human cancellous bone represents a well‐functioning model for qualitative evaluation of bone on‐growth.     

Measuring bone cell adhesion on implant surfaces using a spinning disc device

The adhesion behaviour of osteoblastic cells on implant surfaces is a main focus during the development of osteoconductive implant surfaces. Therefore, besides cell spreading and proliferation on surfaces the adhesion strength of cells to the substrate is of high interest. There are different approaches to determine cell adhesion but only few quantitative methods. For this purpose, we have developed an adhesion device based on the spinning disc principle in conjunction with an inverse confocal laser scanning microscope (LSM). Mirror polished disc‐shaped test samples made of titanium‐ (Ti6Al4V) and cobalt‐alloys (Co28Cr6Mo), as well as stainless steel (316L), were seeded with osteoblasts, stained with a fluorescent dye, at defined radial positions and were incubated for 18 h in cell culture medium (DMEM). After incubation the test samples were placed into the adhesion chamber filled with DMEM. By means of a computer controlled motor the test samples were rotated for 3 min. Using the LSM the detachment of the cells at defined radial positions was determined and the cell count was recorded before and after rotation with the help of imaging software. An average shear stress of 47.1 N/m², 53.2 N/m² and 49.4 N/m² was assessed for the mirror polished Ti6Al4V, Co28Cr6Mo and 316L surfaces respectively. The technique is suitable for studying bone cell adhesion strength on orthopaedic implant materials. Future investigations will focus on different bioactive and anti‐infectious implant surfaces, as well as soluble bioactive factors.     

PolyNaSS grafting on titanium surfaces enhances osteoblast differentiation and inhibits <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> adhesion

Titanium surface modifications to simultaneously prevent bacterial adhesion but promote bone-cell functions could be highly beneficial for improving implant osseointegration. In the present in vitro study, the effect of sulfonate groups on titanium surfaces was investigated with respect to both S. aureus adhesion and osteoblast functions pertinent to new bone formation. Commercial pure titanium (cpTi) squares were oxydized (Tiox), grafted with poly(sodium styrene sulfonate) groups (Tigraft) by covalent bonding using radical polymerization, and were characterized by infrared spectroscopy (HATR-FTIR) and colorimetry. Bacterial adhesion study showed that Tigraft exhibited high inhibition of S. aureus adhesion S at levels >90 %, when compared to cpTi (P < 0.05). In contrast osteoblasts adhesion was similar on all three titanium surfaces. While the kinetics of cell proliferation were similar on the three titanium surfaces, Alkaline phosphatase-specific activity of osteoblasts cultured on Tigraft surfaces was twofold higher than that observed on either on Tiox or cpTi surfaces (P < 0.01). More importantly, the amount and the distribution of calcium-containing nodules was different. The total area covered by calcium-containing nodules was 2.2-fold higher on the Tigraft as compared to either Tiox or cpTi surfaces (P < 0.01). These results provide evidence that poly(sodium styrene sulfonate) groups grafting on cpTi simultaneously inhibits bacteria adhesion but promote osteoblast function pertinent to new bone formation. Such modified titanium surfaces offer a promising strategy for preventing biofilm-related infections and enhancing osteointegration of implants in orthopaedic and dental applications.     

Development of an universal affinity fusion tag (Poly‐DOPA) for immobilizing recombinant proteins on biomaterials

The covalent and non‐covalent immobilization of growth factors such as recombinant human bone morphogenetic protein 2 (rhBMP‐2) on metals and bone replacement materials in bioactive form is a recent development. Up to now the immobilization technology usually involved the chemical modification and activation of the biomaterial surface followed by attachment of the bioactive protein. Here we suggest an alternative method in which an affinity tag fused to an active protein will allow immobilization without additional chemistry. For biomaterials such as minerals, metals (titanium, steel, CoCrMo), glass ceramics, teflon and possibly bone and teeth ideal adhesion molecules would be the foot proteins (Mefps) of the mussel M. edulis which contain the rare amino acid dihydroxy phenylalanine (DOPA). Recently it could be shown by Messersmith's group that a single DOPA‐molecule can be non‐covalently bound to titanium dioxide surface with a dissociation energy of 22.2 kcal/mol (Lee, H.; Scherer, N. F.; Messersmith, P. B. Proc. Natl. Acad. Sci. U. S. A 2006, 103, 12999–13003).We therefore propose the DOPA‐tag as a general and versatile affinity tag for the immobilization of proteins on biomaterials.     

Dextran‐based coating system for the immobilization of cell adhesion promoting molecules on titanium surfaces

Immobilization of adhesive peptides interacting with cellular integrin receptors onto metallic implant surfaces represents a promising approach to improve osseointegration of implants into the surrounding tissue. In the present study, a functional dextran‐based coating system consisting of an amino titanate adhesion promoter with dendritic structure and a carboxymethyl dextran was established to bind an RGD‐containing adhesive peptide via a selective coupling methodology onto titanium surfaces. The three‐step reaction procedure was characterized by X‐ray photoelectron spectroscopy. In cell adhesion experiments it could be demonstrated that dextran coatings containing immobilized RGD promote attachment and spreading of fibroblast and pre‐osteoblastic cells compared to native as well as CMD‐coated titanium surfaces without RGD. The direct attachment of the RGD sequence to the metal surface via the amino titanate adhesion promoter did not increase pre‐osteoblastic cell spreading, whereas coupling of RGD to the polymeric carboxy­methyl dextran layer slightly enhanced spreading of the cells.     

Cell behaviour on phospholipids-coated surfaces

Effective integration of orthopedic biomaterials requires the rapid formation of the inorganic mineral phase during the first hours of implantation and the subsequent adhesion and proliferation of the osteoblasts. It has recently been demonstrated that phosphatidylserine-rich phospholipid coatings can induce a fast mineralisation of titanium implant surfaces on incubation in simulated body fluids. The aim of this work was to investigate the biocompatibility of these coatings in terms of cytotoxicity and ability to support osteoblast adhesion and activity. Cytotoxicity and cell adhesion to uncoated titanium, calcified phospholipid-coated titanium and HA-coated titanium was assessed using fibroblasts and osteoblast-like cells. The synthesis of type I collagen by osteoblast-like cells cultured on the calcified-phospholipid coatings was also comparable to that observed for osteoblast-like cells cultured on the titanium and HA-Ti surfaces. The results suggest that the fast mineralization of the phospholipid matrix, obtained in vitro by its pre-treatment in a SBF, exposes the cells to an environment similar to that present in the bone during its natural formation that allow cells to adhere, proliferate and produce proteins fundamental for bone growth. The biocompatibility of these phospholipid-based coatings, in combination with their ability to initiate rapid mineralisation, provides a promising material that could in vivo create bone cell interactions and bone integration.     

Surface modifications to improve Ti–porcelain bonding

Investigations of surface modifications on cast titanium surfaces and titanium-ceramic adhesion were performed. Cast pure titanium was subjected to surface modification by preoxidation and introduction of an intermediate layer of SnO _x by sol–gel process. Surfaces only sandblasted with alumina were used as controls. Specimen surfaces were characterized by XRD and SEM/EDS. The adhesion between the titanium and porcelain was evaluated by three-point flexure bond test. Failure of the titanium–porcelain with preoxidation treatment predominantly occurred at the titanium-oxide interface. Preoxidation treatment did not affect the fracture mode of the titanium–ceramic system and did not increase the bonding strength of Ti–porcelain. However, a thin and coherent SnO _x film with small spherical pores obtained at 300 °C served as an effective oxygen diffusion barrier and improved titanium–ceramic adhesion. The SnO _x film changed the fracture mode of the titanium–ceramic system and improved the mechanical and chemical bonding between porcelain and titanium, resulting in the increased bonding strength of titanium–porcelain.     

Surface modification of a novel porous titanium dioxide/glass composite

A novel technique is used to produce an open porous titanium dioxide/glass composite, named Ecopore, with promising structural and biological properties for the development as a bone graft. This study aims at a fast and lasting integration of the new material by means of biochemical surface modification. Surface etching of Ecopore, aminosilanization and covalent coupling of the cellular attachment mediator fibronectin was employed as modification strategy. In a comparison of different etching procedures, alkaline etching led to the highest density of amino functions after subsequent aminosilanization. Fibronectin was immobilized using a bifunctional aminoreactive PEG‐linker. This protein coating improved the attachment of human osteoblast‐like cells (HOB) on non‐porous Ecopore as displayed by vital staining. XTT metabolism assays indicated an enhanced HOB growth in the initial phase of cultivation on fibronectin‐coated versus non‐coated specimens. In a first feasibility study, cultivation of HOB on coated porous Ecopore cylinders with a median pore size diameter of 130 μm showed that cellular growth was uniform and dense on the external surface of the specimen, but was sparse in the interior pore system. Ecopore batches with larger pores will be modified and investigated in vitro and in vivo in the next step of the study.     

Formation of OTS self-assembled monolayers at chemically treated titanium surfaces

Enhanced biocompatibility of titanium implants highly depends on the possibility of achieving high degrees of surface functionalization for a low immune response and/or enhanced mineralization of bioactive minerals, such as hydroxyapatite. In this respect, surface modification with Self Assembled Monolayers (SAMs) has a great potential in delivering artificial surfaces of improved biocompatibility. Herein, the effectiveness of common chemical pre-treatments, i.e. hydrogen peroxide (H₂O₂) and Piranha (H₂SO₄ + H₂O₂), in facilitating surface decontamination and hydroxylation of titanium surfaces to promote further surface functionalization by SAMs is investigated. The quality of the octadecyltrichlorosilane (OTS) based SAM appeared to strongly depend upon the surface morphology, the density and nature of surface hydroxyl sites resulting from the oxidative pre-treatments. Contrary to common belief, no further hydroxylation of the titanium substrate was observed after the selected chemical pre-treatments, but the number of hydroxyl groups available on the surface was decreased as a result of the formation of a titanium oxide layer with a gel-type structure. Further examinations by atomic force microscopy, infrared spectroscopy and X-ray photoelectron spectroscopy also revealed that mild oxidizing conditions were sufficient to remove surface contamination without detrimental effects on surface hydroxylation state and surface roughness. Furthermore, the adsorption of the alkylsiloxane molecules forming the SAM film is believed to proceed through hydrolysis at surface acidic hydroxyl groups rather than randomly. This site dependent adsorption process has significant implications for further functionalization of titanium based implants. It also highlights the difficulty of achieving an OTS based SAM at the surface of titanium and question the quality of SAMs reported at titanium surfaces so far.     

Human-osteoblast proliferation and differentiation on grit-blasted and bioactive titanium for dental applications

Physico-chemical and topographical surface quality of commercially pure titanium (c.p. Ti) dental implants is one of the most influencing factors in the improvement of their osseointegration. In this sense, previously, a two-step method (2S) for obtaining bioactive blasted-rough titanium surfaces was developed for improving short-term (due to its bioactivity) and long-term (due to its roughness) osseointegration. This 2S-method consists of: (1) Grit blasting on titanium surface in order to roughen it, and (2) thermo-chemical (TCh) treatment in order to obtain a bioactive surface with bone-bonding ability. The aim of the present work is to evaluate the in vitro human-osteoblast response (proliferation, differentiation – ALP activity- and cell morphology-studied by environmental scanning electron microscopy) of rough c.p. Ti (grit blasted), bioactive c.p. Ti (thermo-chemically treated) and rough-bioactive c.p. Ti (2S-treated). Different grit materials (Al₂O₃ and SiC) have been used in order to investigate their influence. The results showed that cell adhesion was statistically higher for the rough and bioactive surfaces, whatever the grit used. Cells proliferated very well on all the c.p. Ti surfaces. If comparing groups with and without TCh (all other treatments being equal) the ALP was always higher in the groups with TCh, indicating stimulation of osteoblast differentiation because of TCh, more significantlly in the groups that were first blasted. Those ALP results were accompanied by a decrease in the value of proliferation, which shows the good behavior of the cells. This results suggest that a rough and bioactive-titanium surface obtained by 2S-treatment enhances adhesion and differentiation activity of human osteoblasts cells.     

Biocoating of Electropolished and Ultra‐Hydrophilic Titanium and Cobalt Chromium Molybdenum Alloy Surfaces with Proteins

Bone morphogenetic proteins (BMPs) play a decisive role in bone development and osteogenesis. In the past they have been the subject of widespread research and clinical trials as stimulants of bone growth. Although recently recombinant human BMP‐2 (rhBMP‐2) has been chemically immobilized on implant surfaces leading to enhanced bone growth and accelerated integration in vivo, the non‐covalent immobilization of proteins on metal surfaces is still poorly understood, since the oxide layers on metals like titanium, stainless steel or cobalt chromium alloys are poor adsorbents of proteins. Protein binding surfaces could either be generated by linking ionic groups (ion‐exchange surface) or by coupling hydrophobic residues (hydrophobic interacting surface, HIS) to the surface. In this paper the preparation of protein adsorbing surfaces on titanium and cobalt chromium molybdenum alloy for the adsorption of rhBMP‐2 and ubiquitin will be described. rhBMP‐2 and ubiquitin are bound extremely tight to surfaces containing propyl or hexyl groups of a certain surface concentration and are slowly released over a range of at least 24–100 days making such surfaces applicable as long‐term drug delivery devices for enhancing bone growth or implant integration.     

NiTi shape memory alloys coated with calcium phosphate by plasma‐spraying. Chemical and biological properties

Plates of superelastic nickel‐titanium shape memory alloy (NiTi) were coated with calcium phosphate (hydroxyapatite) by high‐temperature plasma‐spraying. The porous layer of about 100 μm thickness showed a good adhesion to the metallic substrate that withstood bending of the plate but detached upon cutting the plate. The biocompatibility was tested by cultivation of blood cells (whole blood and isolated granulocytes [a subpopulation of blood leukocytes]). As substrates, pure NiTi, plasma‐spray‐coated NiTi and calcium phosphate‐coated NiTi prepared by a dip‐coating process were used. The adhesion of whole blood cells to all materials was not significantly different. In contrast, isolated granulocytes showed an increased adhesion to both calcium phosphate‐coated NiTi samples. However, compared to non‐coated NiTi or dip‐coated NiTi, the number of dead granulocytes adherent to plasma‐sprayed surfaces was significantly increased for isolated granulocytes (p<0.01).     

Diatom‐Inspired Silica Nanostructure Coatings with Controllable Microroughness Using an Engineered Mussel Protein Glue to Accelerate Bone Growth on Titanium‐Based Implants

Silica nanoparticles (SiNPs) have been utilized to construct bioactive nanostructures comprising surface topographic features and bioactivity that enhances the activity of bone cells onto titanium‐based implants. However, there have been no previous attempts to create microrough surfaces based on SiNP nanostructures even though microroughness is established as a characteristic that provides beneficial effects in improving the biomechanical interlocking of titanium implants. Herein, a protein‐based SiNP coating is proposed as an osteopromotive surface functionalization approach to create microroughness on titanium implant surfaces. A bioengineered recombinant mussel adhesive protein fused with a silica‐precipitating R5 peptide (R5‐MAP) enables direct control of the microroughness of the surface through the multilayer assembly of SiNP nanostructures under mild conditions. The assembled SiNP nanostructure significantly enhances the in vitro osteogenic cellular behaviors of preosteoblasts in a roughness‐dependent manner and promotes the in vivo bone tissue formation on a titanium implant within a calvarial defect site. Thus, the R5‐MAP‐based SiNP nanostructure assembly could be practically applied to accelerate bone‐tissue growth to improve the stability and prolong the lifetime of medical implantable devices.     

Klebflächenvorbehandlung von Aluminiumoberflächen mit Haftvermittler

Surface pretreatment for adhesive bonding of aluminum with adhesive mediator The influence of three steps pretreatment degreasing, blasting and primer and the two steps pretreatment degreasing and blasting on the adhesive behaviour of aluminum alloy AlMg4,5Mn0,5 were investigated. The investigations were preformed using two cold hardening two‐components epoxy adhesives, one hot hardening one‐component epoxy adhesive and one cold hardening two‐components polyurethane adhesive. The three steps pretreatment indicate that the adhesion bonding strength by epoxy adhesives are higher than that by two steps pretreatment. On the other hand, the adhesion bonding strength was similar by using polyurethane adhesive independence of the pretreatment method. Leaving out the pretreatment step degreasing after corund blasting caused by using, PU, EP 2 and EP 3 adhesives a significant decreasing of the bonding strength in comparison with the only degreased specimen. This degreasing process was used to remove the residual blasting medium from the aluminum surfaces after blasting. The topographical structure of the surfaces after corund blasting was covered by further pretreatment with primer as a consequence of higher primer viscosity, which causes a decreasing in the surface roughness. The chemical composition of pretreated surfaces by three steps was different from that by two steps.     

Niedrigemittierende Außenoberflächen bei Wärmedämmverbundsystemen – ein Studie zur Vermeidung von Algenwuchs

Algae growth on the outside surface of thermal insulating composite systems (TICS) occurs because of long‐lasting wetting. The present techniques for its avoidance are without long‐term effect. Especially, dew and frost are an essential reason for its occurrence because of the highly thermal insulation of the TICSs. In the following report, it will be investigated by an algorithm on the basis of a worst case scenario for outside condensation whether outside condensation on TICSs can be counteracted by a low‐emissivity outside surface as it is well‐proven on highly insulating window glazing. The calculations showed that outside condensation on TICSs with heat transfer coefficients (U) values from 0.1 to 0.2 W/(m² K) cannot be avoided theoretically by thermal emissivity values ε in the range of 0.05 till 0.1. However, because the most critical scenario conditions for outside condensation are very stringent and, in addition, the calculations have shown that outside condensation is only possible for relative outdoor humidity rH_o ≥ 95%, it can be deduced that the occurrence of outside condensation will be very improbably in praxis for TICSs with U values from 0.1 to 0.2 W/(m² K) and ε values from 0.05 to 0.1. A weathering and soiling resistant surface with ε ≤ 0.1 can be realized by aluminum which may be additionally passivated by a titanium dioxide coating. Because of the hydrophilic property, this coating shows also self‐cleaning effect and quickly drying of the surface after rain. The latter may counteract algae growth, too.     

Characterization of electrolytic HA/ZrO2 double layers coatings on Ti–6Al–4V implant alloy

Hydroxyapatite (HA) coating was proved having bioactive property and hence improving the bonding strength on bone tissue without inducing the growth of fiber tissue. However, the weak adhesion between HA and metal implants is still the major problem. In this study, a novel method of electrolytic HA/ZrO₂ double layers coating was successfully conducted on F-136 Ti–6Al–4V implant alloy in ZrO₂(NO₃)₂ aqueous solution and subsequently in the mixed solution of Ca(NO₃)₂ and NH₄H₂PO₄. After annealing at 400 °C, 500 °C and 600 °C for 4 h in air, the coated specimens were evaluated by X-ray diffraction analyses, surface morphology observations, scratch tests, dynamic polarization tests, immersion tests and cell culture assays. In addition to corrosion resistance, the adhesion strength of electrolytic deposited HA on Ti alloy was dramatically improved from the critical scratch load 2 N to 32 N by adding the intermediate electrolytic deposition of ZrO₂, which showed the strong bonding effects between Ti alloy substrate and HA coating. Based on the cell morphology and cell proliferation data, HA/ZrO₂ double layers coating revealed the better substrate for the adhesion and proliferation of osteoblasts than the others. It was also found that the crystallization of HA had positive effect on the proliferation of osteoblasts.     

Bruchmechanische Untersuchung der Titan‐PEEK‐Grenzfläche in thermoplastischen Titan‐CF/PEEK‐Laminaten durch Mixed‐Mode‐Bending‐Versuche

The adhesion and failure mechanism at well‐designed titanium‐PEEK interfaces within Ti‐CF/PEEK laminates are investigated by superposed mode I‐ and mode II‐loading before and after hydrothermal aging. The laser‐induced columnar structured oxide layer enhances the adhesion at the Titanium‐PEEK interface. PEEK‐Polymer that is locked mechanically in the capillary gaps of the columnar oxide structure are stretched and stiffed in the case of loading resulting in good adhesion. The adhesion at the oxide structure reduces by the influence of hydrothermal aging. Basically, the failure mechanism is not changed. Thus, the columnar oxide structure leads to enhanced humidity resistance of the adhesion between titanium and PEEK. The PEEK‐Polymer is also locked in the undercuts between the depressions and rims of the laser‐induced dot‐like surface structure resulting in adhesion. The adhesion at the dot‐like structured surface is nearly completely reduced by the influence of hydrothermal aging. The failure mechanism is changed from ductile failure within the PEEK‐Polymer to party disrupted rims and melt spatter.     

Bioactive TiOB‐Coating on Titanium Alloy Implants Enhances Osseointegration in a Rat Model

The surface properties of titanium alloy implants for improved osseointegration in orthopaedic and dental surgery have been modified by many technologies. Hydroxyapatite coatings with a facultative integration of growth factors deposited by plasma spraying showed improved osseointegration. Our approach in order to enhance osseointegration was carried out by a surface modification method of titanium alloy implants called plasma chemical oxidation (PCO). PCO is an electrochemical procedure that converts the nm‐thin natural occurring titanium‐oxide layer on an implant to a 5 µm thick ceramic coating (TiOB‐surface). Bioactive TiOB‐surfaces have a porous microstructure and were loaded with calcium and phosphorous, while bioinert TiOB‐surfaces with less calcium and phosphorous loadings are smooth. A rat tibial model with bilateral placement of titanium alloy implants was employed to analyze the bone response to TiOB‐surfaces in vivo. 64 rats were randomly assigned to four groups of implants: (i) pure titanium alloy (control), ii) titanium alloy, type III anodization, (iii) bioinert TiOB‐surface, and (iv) bioactive TiOB‐surface. Mechanical fixation was evaluated by pull out tests at 3 and 8 weeks. The bioactive TiOB‐surface showed significantly increased shear strength at 8 weeks compared to all other groups.     

Porous Titanium Coatings Through Electrophoretic Deposition of TiH2 Suspensions

In the biomedical field, modification of titanium surfaces to improve the osteoinductive and antibacterial behavior is widely investigated. This functionalization can be further ameliorated by providing a porous coating with high loading capacity for bioactive materials and drug delivery carriers at the implant surface. In this work, a new powder metallurgical processing route used to deposit such porous pure titanium coatings on Ti based substrates is presented. The coatings were prepared by electrophoretic deposition (EPD) of TiH₂ powder suspensions followed by dehydrogenation and sintering in vacuum. The use of hydrides allowed to lower the sintering temperature below that of the α–β transition of the Ti6Al4V substrate. Measurement of the tensile bond strength confirmed a strong adhesion of the porous coating. Deposition of powders with different grain sizes resulted in porous titanium coatings with varying thickness, pore morphology, and surface roughness. The possibility to extend this coating technique to complex shaped implants is highlighted.     

In‐situ composite coating on powder metallurgy master alloy fabricated by vacuum hot‐pressing sintering technology

A material consisting of an in‐situ titanium carbide reinforced nickel‐aluminide (Ni₃Al) coating and a powder metallurgy master alloy was fabricated by vacuum hot‐pressing sintering technology. A metallurgical bonded, pores‐free interface between composite coating and powder metallurgy master alloy was formed at the sintering temperature of 1050 °C, pressure of 10^‐4 Pa and pressing pressure of 40 MPa. The phase, microstructure and wear behavior of composite coating were investigated. The results showed that polygonal titanium carbide particulates with various sizes were homogeneously distributed in nickel‐aluminide matrix. The sintering temperature, pressing pressure and heat from as‐reactions‐formed coating green compact facilitated the pore infiltration with transiently generated liquid phases and ensured the high‐intensity metallurgical bonding between composite coating and powder metallurgy master alloy. Due to the abnormal elevated‐temperature properties of nickel‐aluminide matrix, titanium carbide particulates reinforcement and the mechanically mixed layer protection, TiC/Ni₃Al‐coated parts demonstrated superior wear resistance and lower friction coefficient while compared with Ni₃Al‐coated parts and H13 steel.