Op s suspension

For phase analysis, samples were cut from different locations along the building direction of the as-fabricated parts and were mechanically polished using Struers OP-S suspension containing 20 vol % of H₂O₂ for 30 min without any chemical etching. The microstructure was characterized in backscattered electron (BSE) mode using an FEI Scios Dual Beam system (Thermo Fisher Scientific Inc., USA) equipped with a concentric backscattered (CBS) detector under 3 kV accelerating voltage, 1.6 nA probe current, and 5.5 mm working distance. For SEM-EDS mapping of as-fabricated parts, the samples prepared for phase analysis were then characterized by using an SEM (JEOL JSM-6610, Japan).

CpTi G4 was used as a substrate for the ECAD of CaP coatings. Composition limits followed the specifications defined in standards ASTM F67-13 [12 ] and ISO 5832-2 [13 ]. Five-mm-high disc-shaped specimens were cut from a 10-mm diameter bar (Bibus Metals, Dąbrowa, Poland). CpTi G4 specimens were subjected to mechanical polishing with 600 to 5000 # grit silicon carbide paper and colloidal silica suspension for finishing polishing with a grain size of 0.04 mm (OP-S suspension, Struers, Cleveland, OH, USA). Polished specimens with a mirror surface were sonicated twice for 20 min, first in acetone and then in ultra-pure water with a resistivity of 18.2 MΩ cm at 25 °C produced by the Milli-Q Advantage A10 Water Purification System (Millipore SAS, Molsheim, France). The CpTi G4 specimens prepared in this way were sandblasted using white Al₂O₃ of FEPA Grit F220 [43 ]. A pressure of 0.6 MPa was used. The sandblasting time was 15 s. The distance of the sand nozzle from the titanium surface was about 1.5 cm. CpTi G4 specimens were washed in an ultrasonic cleaner for 20 min, successively in acetone, and then in ultrapure water to remove corundum residues from sandblasted surfaces. In the next stage, the sandblasted specimens were sterilized in distilled steam at 134 °C under a pressure of 2.2 bar for 90 min using a Zealway Model GR60 DA autoclave (Xiamen, China).

A CpTi G4 rod with a diameter of 10 mm (Bibus Metals, Dąbrowa, Poland) was cut into disk-shaped samples which were 5 mm high. CpTi G4 disks were mechanically pre-polished on 600 to 5000 # grit SiC papers. A colloidal silica suspension with a grain size of 0.04 µm (OP-S suspension, Struers, Cleveland, OH, USA) was used in the final step of the mechanical polishing. Samples with a mirror surface were cleaned in an ultrasonic cleaner for 20 min in acetone, and then in ultrapure water with a resistivity of 18.2 MΩ cm at 25 °C, produced with a Milli-Q^® Advantage A10 Water Purification System (Millipore SAS, Molsheim, France). The polished CpTi G4 samples were sandblasted with a white Al₂O₃ FEPA Grit F220 abrasive [27 ]. Next, they were sonicated again. After drying, the samples were autoclaved using the Zealway Model GR60 DA (Xiamen, China). A detailed description of the conditions of the sandblasting and autoclaving process is given in the earlier work [28 (link)].