Preparation And Study Of Laser Cladding Carbon Nanotubes Reinforced Bioceramic Coatings

The paper is mainly prepared preparation Calcium Phosphate Bioactive Ceramic Coating Reinforced by Carbon Nanotubes on Titanium Alloy by Laser Cladding.The carbon nanotubes enhanced hydroxyapatite bioceramic composite coatings were prepared on the surface of the alloy,with 80% CaHPO₄·2H2O and 20% CaCO₃ mixed powder as the coating raw materials and different mass fraction as the toughening phase of the ceramic coating,by i LS-YC-30 A Nd: YAG laser cladding.This paper studied the influence of the ratio of raw material powder,laser power and sscanning speed on the coating product phase and also evaluated the mechanical and biological properties of the coating material.The preparation of raw materials mixed powder.Firstly,carbon nanotubes were purified and pretreatment.And then CNTs,CaHPO₄·2H2O and CaCO₃ were mixed in proportion and dried and ceramic coating raw materials were prepared.In the same way,the titanium powder and CaHPO₄·2H2O,CaCO₃ mixed powder were mixed at a ratio of 1:1,and the carbon nanotubes with different mass fraction were added to prepare the transition layer.The mixed powders were preliminarily characterized.Observation of mixed powder scanning electron microscopy showed that with the increasing concentration of carbon nanotubes,raw material powder and carbon nanotubes of the degree of integration is getting higher and determine its optimal concentration of 10%.Study on Preparation of Bioceramic Coating by Laser Cladding.The bioceramic composite coatings with hydroxyapatite and calcium pyrophosphate as the main components were prepared by laser cladding with Nd: YAG laser under different process parameters.The macroscopic morphology,phase,structure and related properties of the cladding layer under different process parameters were analyzed and studied to determine the optimum laser cladding process parameters.In order to prepare the appearance of qualified laser cladding,the writer must do the experiment in the output power of 600-1500 W,scanning speed of 1-4mm/s.When the scanning rate of 1mm/s and the laser power of 600 W,the hydroxyapatite began to appear.And with the lift laser power,hydroxyapatite content gradually increased;when the laser power rose to 900-1100 W,the hydroxyapatite content More;when the laser power rose to 1200 W,the hydroxyapatite content gradually decreased,calcium pyrophosphate gradually increased,and the cladding began to burn.Under the experimental conditions,the optimum process parameters are tentative as follows: scanning speed V =1 mm/s,laser power P=1000W,spot diameter D=4mm.Study on Mechanical Properties and Corrosion Resistance of Bioceramic Composite Coatings.The microhardness,bond strength,tensile strength,flexural strength,elastic modulus and corrosion resistance of the bioceramic composite coating were tested and analyzed in this paper.The microhardness of the bioceramic composite coating is greatly improved,and the maximum value is 885 MPa.The bonding strength between the bioceramic composite coating and the metal matrix is 42.0MPa.Its tensile strength is 888.2MPa.Its bending strength is 443.0MPa,and its elastic modulus is 146.76 GPa.The corrosion resistance test shows that the bioceramic composite coating is better than the corrosion resistance of titanium alloy.Study on Biological Properties of Bioceramic Composite Coatings.The biocompatibility and bioactivity of bioceramic composite coatings were characterized by simulated body fluid culture experiments.Thus,the carbon nanotubes reinforced bioceramic composite coating formed on the surface of titanium alloy with laser cladding technology owns a good combination with the matrix and has excellent mechanical properties and biological activity.It is a comprehensive performance Good biological hard tissue alternative material.