Research On The Technology And Properties Of Porous Titanium Based On Titanium Hydride

Titanium and titanium alloys have good chemical corrosion resistance and good biochemical compatibility,low elastic modulus and high specific strength,which have attracted the attention of many scholars and have broad prospects in medical bone replacement and teeth.Titanium’s abundance in nature is relatively high,but because of its relatively lively,smelting and processing costs are relatively high,which limits his use.Powder metallurgy is an effective method to obtain low-cost titanium.Titanium is used as a bone replacement material in the medical field,but titanium and its alloys have higher modulus of elasticity and compressive strength than bone and mismatched mechanical properties,which can easily cause stress shielding and cause implant failure.Reducing the elastic modulus of titanium to match the mechanical properties with bone,and then modifying the surface of titanium to improve biocompatibility has been one of the key directions of titanium bone implant research.Through the powder metallurgy method,the introduction of pores in titanium can effectively adjust the elastic modulus and mechanical properties of titanium.In this study,titanium hydride and other alloy powders were used as raw materials,sodium chloride and ammonium bicarbonate as pore-forming agents,and porous titanium and porous titanium alloys were prepared by vacuum sintering.Firstly,the influence of technological factors such as pressing pressure,sintering temperature and holding time on the density of titanium,and the relationship between the content and type of pore-forming agent and the porosity of the titanium porous body were studied;Mechanical properties,and fitting analysis and experimental verification of porous mechanical properties based on a large number of experimental data.The main research conclusions are as follows:（1）Molding pressure,sintering temperature and holding time will all affect the porosity and pore size.In the case of no pore-forming agent,change the pressing pressure to prepare pure titanium samples to observe the density,the density increases with the increase of sintering temperature and sintering time,but the change is not great.When the pressing pressure is155MPa,the density is 91.13%.With the increase of pressure,the density gradually increases.When the pressing pressure increases to 388MPa,the density increases to 95.57%.Choose a pressing pressure of 280MPa and add a mass of 30wt.%NH₄HCO₃.When the sintering temperature is 950℃,the corresponding porosity is 52.34%,when the temperature is increased to 1200℃,the porosity is 47.22%,and when the temperature is increased by 250℃,the porosity decreases by 5%About;using titanium hydride to prepare compacts at 280MPa,set the sintering temperature to 1100℃,holding time were 1.5h,2h,2.5h,with the increase of holding time the sample density gradually increased.The density was 94.56%at 1.5 hours of heat preservation and 96.31%at 2.5 hours of heat preservation.The heat preservation time was extended from 1.5 hours to 2.5 hours and the density increased by only 1.75%.（2）By adding 10wt.%～60wt.%Pore-forming agent,porous titanium is prepared.The porosity range when ammonium bicarbonate is used as pore-forming agent is 22.38%-73.24%.The rate ranges from 9.75%to 66.86%.（3）The results of SEM\XRD\metallographic analysis show that when different mass percentages of ammonium bicarbonate and sodium chloride are added as pore-forming agents,good porous titanium is prepared without introducing impurities,and its structure isα-titanium.When the added amount is less than 30wt.%,The connectivity of the pores is low,making it difficult to form a three-dimensional connection.There are two types of pore distribution,one is larger pores of several hundred microns,and the other is smaller pores of tens of microns to several microns,the content of pore-forming agent increases,the pore wall gradually thins,pores overlap each other,so It becomes larger and this composite pore meets the growth requirements of bone tissue.（4）The static compressive properties of porous titanium.From the stress-strain curve,the prepared porous titanium conforms to the typical three-stage mechanical behavior and elastic stage,platform stage,and densification stage of porous materials.The higher-rate porous titanium has an obvious platform stage,while the low-porosity platform is not obvious,and the mechanical properties of the prepared porous titanium meet the needs as an implant material.（5）By analyzing the experimental data,the prepared porous titanium has a certain relationship between elastic modulus,yield strength and porosity.By fitting it with the Gibson-Ashby model formula,the relevant constants consistent with this experiment are obtained.（6）By using the experience of preparing porous titanium,adding self-made nano silver to prepare silver-containing porous titanium,it provides a new idea for the preparation of antibacterial porous titanium materials,and adding Nb and Zr H₂powder to prepare Ti-13-Nb-13Zr low elasticity mold The amount of porous titanium alloy.