Figure 2 shows the FT-IR spectra of Ca(NO₃)₂·4H₂O with weak sharp absorption peak bands at 742, 821, and 1048 cm⁻¹, a strong broad absorption band at 1354 cm^-1, and a strong shoulder absorption band at 1455 cm⁻¹. A wide broad absorption band peak appears at 3442 cm⁻¹ due to the presence of water. Figure 3 shows the FT-IR spectra of HA-Zn powder scrapped from CpTi specimens; the band at ~421 cm⁻¹ may be due to the stretching vibrational mode of Zn–O. The absorption bands at 669 cm⁻¹ and around 3448 cm⁻¹ are due to the stretching vibration and the bending of the O–H bond that contributes in hydrogen bond formation between water molecules adsorbed by hydroxyapatite and potassium bromide used for pellet preparation. The wide broad absorption band in the area of 1033–1269 cm^-1 wave number is attributed to the stretching vibrations of P–O bonds in the phosphate group (PO₃ ⁻⁴). The low-intensity band presented in the area of 1422–1518 cm⁻¹ wave numbers is attributed to the stretching vibration of the C–O bond of the carbonates (CO₃ ⁻²).

Figures 4, 5, and 6 show the SE microphotographs of CpTi specimens coated with HA-Zn, the specimens’ surface is homogenously covered with evenly distributed globular/rosette-like nano-structures that tend to aggregate in characteristic cluster forms with little intervening porosity. On the other hand, Figs. 7, 8, and 9 show the SE microphotographs of control CpTi specimens with blanc surfaces; only the cutting lines of machining appear. The EDS analysis of HA-Zn shows the presence of zinc, titanium, calcium, and phosphorus; the atomic ratio of Ca/P is 1.67 (Fig. 10). However, the control specimen only contains titanium element (Fig. 11).

Table 1 shows the mean average roughness value of the HA-Zn coated and control specimens; the average roughness is 0.34 μm for the control group and increased significantly to be 1.09 μm for the HA-Zn-coated group (P = 0.009) when compared using a pair comparison of the Student t test using SPSS version 20.