Magnesium phosphate (MgP) has garnered growing interest in hard tissue replacement processes due to having similar biological characteristics to calcium phosphate (CaP). In this study, an MgP coating with the newberyite (MgHPO₄·3H₂O) was prepared on the surface of pure titanium (Ti) using the phosphate chemical conversion (PCC) method. The influence of reaction temperature on the phase composition, microstructure, and properties of coatings was systematically researched with the use of an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a laser scanning confocal microscope (LSCM), a contact angle goniometer, and a tensile testing machine. The formation mechanism of MgP coating on Ti was also explored. In addition, the corrosion resistance of the coatings on Ti was researched by assessing the electrochemical behavior in 0.9% NaCl solution using an electrochemical workstation. The results showed that temperature did not obviously affect the phase composition of the MgP coatings, but affected the growth and nucleation of newberyite crystals. In addition, an increase in reaction temperature had a great impact on properties including surface roughness, thickness, bonding strength, and corrosion resistance. Higher reaction temperatures resulted in more continuous MgP, larger grain size, higher density, and better corrosion resistance.

Phosphate chemical conversion (PCC) technology has attracted extensive attention for its ability to regulate the surface properties of biomedical metals. However, titanium (Ti)-based alloys exhibit inertia because of the native passive layer, whereas zinc (Zn)-based alloys show high activity in acidic PCC solutions. The substrate performance affects the chemical reaction in the phosphating solution, which further leads to diversity in coating properties. In this work, the zinc-phosphate (ZnP) coatings are prepared on Ti alloy (TA) and Zn alloy (ZA) substrates using the PCC method, respectively. The coatings prepared herein are detected by a scanning electron microscope (SEM), X-ray diffractometer (XRD), laser scanning confocal microscope (LSCM), universal testing machine, contact angle goniometer, and electrochemical workstation system. The results show that the substrate performance has little effect on the phase composition but can significantly affect the crystal microstructure, thickness, and bonding strength of the coatings. In addition, the ZnP coatings improve the surface roughness of the substrates and show good hydrophilicity and electrochemical corrosion resistance. The formation mechanism of the ZnP coating is revealed using potential-time curves, indicating that the metal–solution interfacial reaction plays a dominant role in the deposition process.

Strontium (Sr) is a trace element in the human body that can promote bone formation and inhibit bone absorption. A conversion coating of strontium phosphate (Sr-P) on the surface of titanium (Ti) can improve its biological properties and has many potential applications in the fields of dentistry and orthopedics. In the present study, Sr-P coatings with SrHPO₄ and Sr₃(PO₄)₂ crystals on Ti are prepared by a phosphate chemical conversion (PCC) treatment and the effect of pH values on the properties of the Sr-P coatings is researched. The results prove that the phase composition, morphology, and corrosion resistance of the coated Ti vary according to the pH values of the PCC solution. The morphology of the conversion deposition on Ti changes from plat-like to cluster-like and then to homogeneous microcrystals as the pH value changes from 2.50 to 3.25. Only discrete SrHPO₄ crystals are generated on the substrate at lower pH values, while relatively stable Sr₃(PO₄)₂ and SrHPO₄ crystals grow and subsequently form an integrated coating on the Ti as the pH exceeds 2.50. The cross-sectional morphologies and bonding strength of different coatings are also researched. The corrosion resistance of coated Ti improves compared with that of bare Ti because of the Sr-P coatings with a Sr₃(PO₄)₂ phase. In addition, it is indicated that the Sr-P coatings on Ti can improve the adhesion and differentiation of BMSCs.

Strontium (Sr) is a trace element in human body that able to promote bone formation and inhibit bone absorption. The conversion coating of strontium phosphate (Sr-P) on the surface of titanium (Ti) can improve its biological properties, and has a wide application prospect in the fields of dentistry and orthopedics. In this present study, Sr-P coatings with SrHPO4 and Sr3(PO4)2 crystals on Ti are prepared by phosphate chemical conversion (PCC) treatment. And the effect of pH on the properties of Sr-P coatings is researched. The results prove that phase composition, morphology and corrosion resistance of coated Ti are different with the pH values in PCC solution. The morphologies of conversion deposition on Ti change from plat-like to cluster-like, and then homogeneous microcrystals, as pH value changed from 2.50 to 3.25. Only discrete SrHPO4 crystals are generating on substrate at lower pH value, while relative stable Sr3(PO4)2 and SrHPO4 crystals are growing and subsequently forming an integrated coating on Ti as pH is higher than 2.50. The corrosion resistance of coated Ti improves comparing with that of bare Ti because of forming Sr-P coatings with Sr3(PO4)2 phase. In addition, it is indicated that the Sr-P coatings can improve the adhesion and differentiation of BMSCs.