Patent Application
20240360582
The present disclosure relates to a method for forming a superhydrophilic oxide film on a pure titanium surface.
In general, metals are subjected to anodization as a method for improving strength or hardness as well as corrosion resistance or wear resistance. In particular, since it has refined pores as well as improved physical properties when titanium or titanium alloy among the metals is surface-treated through anodization, it is widely applied to aviation materials, precision mechanical parts, or the like.
Here, the anodization is one of the most widely known treatment methods among metal surface treatment methods. It is a treatment method for improving physical properties of the base material by forming an oxide film as the surface of the base material is oxidized by oxygen generated from the anode when electricity is applied to a metal base material (e.g., titanium base material) deposited in an electrolyte solution as an anode. That is, oxygen ions or hydroxyl ions in the electrolyte solution penetrate into the oxide film formed on the surface of the base material and combine with metal ions to form an oxide layer, and thus, a porous oxide film and a hydroxide film are grown in the vicinity of the interface between the base material and the oxide layer, thereby further improving the physical properties of the base material.
Therefore, in increasing the physical properties of titanium or titanium alloy above (hereinafter collectively referred to as titanium) by the anodization, it is more important than anything else to properly set various functions such as anodization voltage, time, and the purity of the base material metal as the most important variables of the anodization treatment.
There are Ti grades 1 to 4 with a titanium content of 99 wt. % or more, which are classified as pure titanium, and contain 1 wt. % or less of C, Fe, H, N, and O elements. The titanium alloy contains about 90 wt. % of titanium and about 10 wt. % of other elements. For example, the Ti-6Al-4V grade 5 titanium alloy may contain about 6 wt. % of Al, about 4 wt. % of V, about 90 wt. % of Ti, and trace amounts of Fe and O elements.
Since the desired anodization treatment conditions may vary depending on the titanium content, the titanium content of a titanium substrate to be treated may be said to be important.
Titanium is an indispensable material for flagship industries such as shipbuilding, plants, automobiles, and pigments, and even for future high-tech industries such as defense, aerospace, and medical, due to its excellent high strength, corrosion resistance, human body compatibility, etc. The market size thereof is also expected to grow significantly.
Considering the importance of titanium, the Ministry of Trade, Industry and Energy selected the titanium project as one of the 13 major industrial engine projects in November 2014, and predicted that the world market for titanium would grow from 250 trillion won in 2012 to 600 trillion won in 2025.
Titanium is mainly used for aerospace, medical, and plants, and aircraft parts are used for landing gear, exhaust system, wing structure, and engine system. The proportion of titanium parts for civil aircraft increased from 1 to 3% in 1970 to 9% in 2000 and 12 to 15% in 2010, and the proportion of titanium parts for military aircraft increased from 10% in 1970 to 22 to 40% in 1990. It is mainly used in large aircraft such as Boeing 787, Airbus A380, and A350 as representative examples of civil aircraft.
For national defense, it is widely used in various fields such as tanks, armored vehicles, submarines, and rifles. As titanium replaces existing bulletproof materials in order to reduce weight due to the increase in the weight of tanks, there is a trend that its usage is on the rise.
For plant uses, markets for petrochemicals, heat exchangers, and desalination facilities are steadily growing, and for medical uses, artificial joints and implant procedures are increasing due to aging and medical technology development.
The present inventor found conditions for forming a superhydrophilic oxide film by optimizing time and voltage in anodization treatment, and completed the present disclosure.
An object of the present disclosure is to provide a method for forming a superhydrophilic oxide film on a titanium surface.
Other object of the present disclosure is to provide titanium on which a superhydrophilic oxide film prepared by the above method is formed.
Another object of the present disclosure is to provide titanium on which an oxide film having a surface roughness value of an average roughness of 15 or more and a root mean square roughness (RMS) of 20 or more prepared by the above method is formed.
Another object of the present disclosure is to provide a medical device, a biotransplantation material, an aviation part, an aerospace part, a precision machine part, or a plant part containing titanium manufactured by the above method.
In order to achieve the aforementioned objects, the present disclosure provides a method for forming a superhydrophilic oxide film on a titanium surface, the method including the steps of: polishing the titanium (Ti) surface (step 1); and anodizing polished titanium (Ti) at 10 to 110 V for 1 to 30 minutes to form an oxide film on the titanium surface (step 2).
Titanium may be pure titanium of any one of Ti grades 1 to 4 having a Ti content of 99 wt. % or more.
One or more of electrochemical polishing and chemical polishing may be applied to the polishing in the step 1, and any polishing method may be applied without any limitation if it is known in the art.
The anodized electrolyte in the step 2 may use a mixture of NH4F, water, and ethylene glycol, and as an example in the present disclosure, 150 mL of ethylene glycol containing 0.25 wt. % of NH4F and 2 vol. % of water was used as an electrolyte, but is not limited thereto.
The step 2 may be anodizing polished titanium (Ti) at 90 to 110 V for 5 to 15 minutes, preferably at 95 to 105 V for 7 to 13 minutes, and more preferably at 99.5 to 102 V for 9.5 to 11 minutes.
In order to realize superhydrophilicity with a contact angle of 20° or less, it is preferable to perform anodization at 99.5 to 102 V for 9.5 to 11 minutes, and there may be a problem in that superhydrophilicity cannot be implemented if it is out of this condition.
Furthermore, the present disclosure provides titanium on which a superhydrophilic oxide film prepared by the above method is formed.
Furthermore, the present disclosure provides titanium on which an oxide film having a surface roughness value of an average roughness of 15 or more and a root mean square roughness (RMS) of 20 or more prepared by the above method is formed.
Furthermore, the present disclosure provides a medical device, a biotransplantation material, an aviation part, an aerospace part, a precision machine part, or a plant part containing titanium manufactured by the above method.
The method for forming a superhydrophilic oxide film on a titanium surface according to the present disclosure has the effect capable of realizing superhydrophilicity with a contact angle of 20° or less by optimizing time and voltage under anodization treatment conditions.
Hereinafter, the present disclosure will be described in more detail by the following Examples. However, the following Examples are only to illustrate the present disclosure, and the content of the present disclosure is not limited by the following Examples.
After degreasing the pure titanium substrate using acetone and ethanol, electrochemical polishing and chemical polishing were sequentially performed as shown in Table 1 below.
Next, anodization treatment was performed under the conditions as shown in Table 1 below.
Recognizing that 10 minutes as the anodization treatment time in this embodiment is the most optimal condition for realizing superhydrophilicity, in the following experimental examples, and experiments were conducted to find out the optimum conditions for fixing the anodization treatment time at 10 minutes, adjusting the applied voltage, and realizing superhydrophilicity.
Experiments were conducted to find out the surface shape, thickness, and roughness of the oxide film formed on the surface of pure titanium that had completed anodization treatment in Examples.
As shown in
As shown in
In order to find out the hydrophilicity of the samples subjected to anodization treatment in Examples, contact angle experiments were performed. The experiment was performed 5 times in total to obtain an average value.
As shown in
In summary of the results of Experimental Examples 1 and 2, the contact angle of the oxide film surface is thought to be caused by the correlation between two factors, pore size and roughness, and it can be seen that the larger the pore size, or the larger the roughness value, the lower the contact angle. Even if the roughness value is small, the contact angle can be thought to be lowered by complementing this if the pore size becomes large.
Hereinafter, an experiment was conducted to derive anodization treatment conditions for implementing superhydrophilicity in Experimental Example 3.
In Examples, the average values obtained by measuring five times the contact angles of the samples obtained by fixing the applied voltage to 100 V and adjusting only the time are shown in Table 2 below.
As shown in Table 2 above, it can be confirmed that superhydrophilicity is implemented in the samples treated for 9.5 to 11 minutes.
In Examples, the average values obtained by measuring five times the contact angles of the samples obtained by fixing the treatment time to 10 minutes and adjusting only the applied voltage level are shown in Table 3 below.
As shown in Table 3 above, it can be confirmed that superhydrophilicity is implemented in the samples treated at 99.5 to 102 V.
Comprehensively, it can be confirmed that a superhydrophilic oxide film with a contact angle of 20° or less is formed on the pure titanium surface subjected to anodization treatment by applying a voltage of 99.5 to 102 V for 9.5 to 11 minutes.
So far, the present disclosure has been looked at with respect to its preferred embodiments. Those skilled in the art to which the present disclosure pertains will be able to understand that the present disclosure can be implemented in a modified form without departing from the essential characteristics of the present disclosure. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present disclosure is shown in the claims rather than the foregoing description, and all differences within the scope equivalent thereto will be construed as being included in the present disclosure.
