Method for producing polymeric sol of calcium phosphate compound and method for coating the same on a metal implant

A method for coating a calcium phosphate ceramic on a metal implant, comprising:

• a first step of preparing a calcium salt solution, containing calcium ethoxide dissolved in organic acid, and a phosphate solution, containing triethyl phosphite or triethyl phosphate dissolved in the organic acid;
• a second step of mixing the calcium salt solution with the phosphate solution to produce a mixed solution, and aging the mixed solution at room temperature for a maximum of one week or at 80° C. for a maximum of ten hours to produce a polymeric sol of a calcium phosphate compound;
• a third step of coating the polymeric sol on a surface of the metal implant;
• a fourth step of hydrolyzing a coated layer, including the polymeric sol, on the metal implant;
• a fifth step of preheating the hydrolyzed coated layer on the metal implant to burn organics remaining in the hydrolyzed coated layer;
• a sixth step of repeating the first to fifth steps to desirably increase a thickness of the preheated-coated layer;
• and
• a seventh step of sintering the resulting metal implant at 500 to 800° C. under a nitrogen atmosphere.