KR102446232B1 - Method for correlation analyzing the surface energy between liquid and solid - Google Patents

Abstract

The present invention provides a first step of calculating the polar surface energy (γ _LP ) and non-polar surface energy (γ _LD ) of a liquid, and a second step of calculating the polar surface energy (γ _SP ) and non-polar surface energy (γ _SD ) of a solid and a third step of analyzing the interaction between the liquid and the solid interface.

Description

Method for correlation analyzing the surface energy between liquid and solid}

The present invention relates to a method for analyzing the surface energy correlation between a liquid and a solid, and more particularly, by using the OWRK model to calculate the polar surface energy and non-polar surface energy of liquid and solid, the interaction between the liquid and solid interface It relates to a method for analyzing the surface energy correlation between liquids and solids that can analyze

In tribological systems, lubrication plays an important role in terms of durability. Typically, engine oil is used for smooth and high-speed motion of an automobile engine, and the engine oil plays an important role in terms of efficiency and durability in automobiles. In recent years, interest in low-viscosity engine oil has increased in order to improve engine efficiency (fuel efficiency) from the existing high-viscosity engine oil.

In the existing friction system, there was mainly interest in the characteristics of a large scale (bulk) such as density and viscosity of engine oil. However, due to the development of a low roughness surface and the development of various chemical additives due to the recent development of processing technology, the engine oil and the engine oil Various analytical methods have been applied from a microscopy point of view to understand the interaction at the metal interface in contact with the metal.

However, in the conventional analysis method, by analyzing the polar surface energy and the non-polar surface energy of the liquid and the solid, a method for analyzing the interaction between the liquid and the solid interface is not presented.

KR 10-2054856 B1

The present invention has been devised to solve the above problems, and an object of the present invention is to calculate the polar surface energy and non-polar surface energy of liquid and solid using the OWRK model, and the interaction between the liquid and solid interface An object of the present invention is to provide a method for correlating the surface energy of liquids and solids that can analyze

In order to solve the above technical problems, the surface energy correlation analysis method of the liquid and the solid according to an embodiment of the present invention is to calculate the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the liquid A first step, a second step of calculating the polar surface energy (γ _SP ) and the non-polar surface energy (γ _SD ) of the solid, and a third step of analyzing the interaction between the liquid and the solid interface.

In addition, the first step is a first step of measuring the total surface energy (γ _L ) of the liquid and the contact angle (θ _PTFE ) of the liquid on the surface of the fluororesin (PTFE), the total surface energy of the liquid (γ L ) _L ) and the contact angle (θ _PTFE ) of the liquid on the surface of the fluororesin by substituting the equation γ _LD = (γ _L (cosθ _PTFE +1)) ² /80 to calculate the non-polar surface energy (γ _LD ) of the liquid and substituting the total surface energy (γ _L ) and non-polar surface energy (γ _LD ) of the liquid into the formula γ _LP =γ _L -γ _LD , and the polar surface energy of the liquid (γ _LP ) It is characterized in that it includes steps 1-3 of calculating

In addition, in the second step, for two liquids for which the polar surface energy (γ _L2P ) and the non-polar surface energy (γ _L2D ) are known in advance, the contact angle (θ _S2 ) of the liquid on the solid surface is measured, respectively. For step 2-1 and the above two liquids, the polar surface energy (γ _L2P ), non-polar surface energy (γ _L2D ), total surface energy (γ _L2 ) and contact angle of the liquid on the solid surface (θ _S2 ) of the liquid By substituting each of the formulas (γ _SD γ _L2D ) ^1/2 +(γ _SP γ _L2P ) ^1/2 =0.5γ _L2 (cosθ _S2 +1), the polar surface energy (γ _SP ) and the non-polar surface energy of the solid (γ _SD ) It is characterized in that it includes a step 2-2 of calculating.

In addition, in the third step, for the liquid of the first step and the solid of the second step, using the formula ΔG _SL =-2[(γ _SD γ _LD ) ^0.5 +(γ _SP γ _LP ) ^0.5 ], In the 3-1 step of calculating the Gibbs free energy ( _{ΔG SL ) of} Step 3-2 of calculating the compatibility of a solid surface reference, Step 3-3 of measuring the contact angle (θ _S ) of the liquid on the solid surface and the compatibility and the contact angle of the liquid on the solid surface ( θ _S ) It is characterized in that it includes the third and fourth steps of comparing.

In the method for analyzing the surface energy correlation between liquid and solid according to an embodiment of the present invention, the engine oil and the engine oil and Wettability of the engine oil to the metal surface by analyzing the interaction of the engine oil and metal interface by calculating the ratio of polar and non-polar or dispersive components of the metal in contact has a predictable effect.

1 is a flowchart of a method for analyzing the surface energy correlation between a liquid and a solid according to an embodiment of the present invention.
FIG. 2 is a flowchart for step S100 shown in FIG. 1 .
FIG. 3 is a flowchart for step S200 shown in FIG. 1 .
FIG. 4 is a flowchart for step S300 shown in FIG. 1 .
5 is a graph showing the measurement results of the contact angle (θ _PTFE ) of the engine oil on the surface of the fluororesin for three types of engine oil.
6 is a graph showing the calculation results of total, non-polar, and polar surface energy (γ _L , γ _LD , γ _LP ) for three engine oils.
7 is a graph showing the measurement results of the contact angle of water on the metal surface for three types of metals.
8 is a graph showing the measurement results of the contact angle of the DIM on the metal surface for three types of metals.
9 is a graph showing the calculation results of total, non-polar, and polar surface energies (γ _S , γ _SD , γ _SP ) for three metals.
10 is a graph showing the results of calculation of suitability for three types of engine oil and three types of metals.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings in order to describe in detail enough that a person of ordinary skill in the art to which the present invention pertains can easily implement the technical idea of the present invention.

However, the following examples are merely examples to help the understanding of the present invention, thereby not reducing or limiting the scope of the present invention. In addition, the present invention may be embodied in several different forms and is not limited to the embodiments described herein.

1 is a flowchart of a method for analyzing the surface energy correlation between a liquid and a solid according to an embodiment of the present invention. Referring to Figure 1, the method for analyzing the surface energy correlation between the liquid and the solid according to an embodiment of the present invention comprises the steps of calculating the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the liquid (S100), It consists of calculating the polar surface energy (γ _SP ) and the non-polar surface energy (γ _SD ) of the solid ( S200 ) and analyzing the interaction between the liquid and the solid surface ( S300 ).

First, the step of calculating the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the liquid ( S100 ) will be described.

In the method for analyzing the surface energy correlation between liquid and solid according to an embodiment of the present invention, the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the liquid are used using the Owens-Wendt-Rabel-Kaelble (OWRK) model. ) can be calculated.

First, the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the liquid, the polar surface energy (γ _SP ) and the non-polar surface energy (γ _LD ) of the solid are related to the relational equations (1).

(Equation 1)

(γ _SD γ _LD ) ^1/2 +(γ _SP γ _LP ) ^1/2 =0.5γ _L (cosθ+1)

Here, γ is the surface energy, and the subscripts S and L are solid and liquid, respectively. And, the subscripts P and D are polar and nonpolar (nonpolar or dispersive), respectively, and θ means the contact angle of the liquid on the solid surface.

(Equation 2)

γ _LP =γ _L -γ _LD

Here, γ _LP , γ _L and γ _LD mean the polar surface energy of the liquid, the total surface energy of the liquid and the non-polar surface energy of the liquid, respectively.

(Equation 3)

γ _S =γ _SP +γ _SD

Here, γ _S , γ _SP and γ _SD mean the total surface energy of the solid, the polar surface energy of the solid, and the non-polar surface energy of the solid, respectively.

Although the total surface energy (γ _L ) of a liquid, that is, the surface tension of a liquid, can be easily measured, it is difficult to directly measure the polar surface energy (γ _LP ) of a liquid or the non-polar surface energy (γ _LD ) of a liquid.

In this case, the total surface energy of the liquid (γ _L ) and the contact angle of the liquid (θ _PTFE ) on the solid surface where the non-polar surface energy (γ _SD ) is 0, such as a fluororesin (PTFE, Polytetrafluoroethylene), is measured in Equation 1 Substituting this, we can easily calculate the nonpolar surface energy (γ _LD ) of the liquid.

Specifically, after substituting the total surface energy γ _S = 20 of the fluororesin, the polar surface energy γ _SP = 20 of the fluororesin, and the non-polar surface energy γ _SD = 0 of the fluororesin into Equation 1, the non-polar surface energy of the liquid ( γ _LD ) is summarized as in Equation 4.

(Equation 4)

γ _LD =(γ _L (cosθ _PTFE +1)) ² /80

Here, γ _LD , γ _L and θ _PTFE mean the nonpolar surface energy of the liquid, the total surface energy of the liquid and the contact angle of the liquid in the plane of the fluororesin, respectively.

First, by substituting the pre-measured total surface energy (γ _L ) of the liquid and the contact angle of the liquid on the fluororesin surface (θ _PTFE ) into Equation 4, the non-polar surface energy (γ _LD ) of the liquid is calculated. After that, by substituting the nonpolar surface energy (γ _LD ) of the liquid and the total surface energy (γ _L ) of the liquid into Equation 2, the polar surface energy (γ _LP ) of the liquid can be easily calculated.

Accordingly, the step (S100) of calculating the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the liquid is summarized as follows.

FIG. 2 is a flowchart for step S100 shown in FIG. 1 .

Referring to Figure 2, using the Ring method (SEO's surface tension analyzer), the total surface energy (γ _L ) of the liquid is measured. After that, using a sessile drop (Smartdrop from Femtobiomed), the contact angle (θ _PTFE ) of the liquid on the surface of the fluororesin is measured. (S110)

After that, the total surface energy (γ _L ) of the liquid measured in step S110 and the contact angle (θ _PTFE ) of the liquid on the surface of the fluororesin are calculated in Equation 4, γ _LD = (γ _L (cosθ _PTFE +1)) ² /80 Substituting into , calculate the non-polar surface energy (γ _LD ) of the liquid (S120).

After that, by substituting the total surface energy (γ _L ) of the liquid measured in step S110 and the non-polar surface energy (γ _LD ) of the liquid calculated in step S120 into Equation 2, γ _LP =γ _L -γ _LD , the liquid Calculate the polar surface energy (γ _LP ) of (S130)

Next, the step of calculating the polar surface energy (γ _LP ) and the non-polar surface energy (γ _LD ) of the solid ( S200 ) will be described.

FIG. 3 is a flowchart for step S200 shown in FIG. 1 .

Referring to FIG. 3 , for two liquids for which the polar surface energy (γ _L2P ) and the non-polar surface energy (γ _L2D ) of the liquid are known in advance, the contact angle (θ) of the liquid on the solid surface using the static method _S2 ) is measured, respectively. (S210)

Then, for the above two liquids, the contact angle of the liquid at the solid surface (θ _S2 ), the polar surface energy of the liquid (γ _L2P ), the non-polar surface energy of the liquid (γ _L2D ), and the total surface energy of the liquid (γ _L2 ) ) in Equation 1, (γ _SD γ _L2D ) ^1/2 + (γ _SP γ _L2P ) ^1/2 =0.5γ _L2 (cosθ _S2 +1) by solving the simultaneous equations, the polar surface energy of the solid ( Calculate γ _SP ) and non-polar surface energy (γ _SD ). (S220)

Next, the step of analyzing the interaction between the liquid and the solid surface (S300) will be described.

FIG. 4 is a flowchart for step S300 shown in FIG. 1 . Referring to FIG. 4 , for the liquid in step S100 and the solid in step S200, using Equation 5, the Gibbs free energy (ΔG _SL ) of the interface is calculated. (S310)

Equation 5 for calculating the Gibbs free energy (ΔG _SL ) of the interface is as follows.

(Equation 5)

ΔG _SL =-2[(γ _SD γ _LD ) ^0.5 +(γ _SP γ _LP ) ^0.5 ]

Here, ΔG _SL means the Gibbs free energy of the interface.

And, as shown in Equation 6, the absolute value of the value obtained by subtracting the surface energy (γ _L ) of the liquid in step S100 from the absolute value of the Gibbs free energy (ΔG _SL ) of the interface, compatibility of the solid surface standard Calculate. (S320)

(Equation 6)

Compatibility=abs(abs(ΔG _SL )-γ _L )

In this case, it is determined that suitability is high as the calculation result of Equation 6 is relatively large, and suitability is low as the calculation result of Equation 6 is relatively small.

After that, using the static method, the contact angle (θ _S ) of the liquid in step S100 is measured on the solid surface of step S200. (S330)

Thereafter, the suitability calculated in step S320 and the contact angle θ _S of the liquid on the solid surface measured in step S330 are compared. (S340)

(Experimental Example 1)

In Experimental Example 1, polar surface energy (γ _LP ) and non-polar surface energy (γ _LD ) were calculated for three engine oils (0w16, 5w30, 10w60) having different viscosities.

First, using the Ring method, the total surface energy (γ _L ) of the engine oil at 25 ℃ was measured.

after that. Using the static method, the contact angle (θ _PTFE ) of the engine oil on the surface of the fluororesin was repeatedly measured at room temperature 10 times or more.

The measurement results of the total surface energy (γ _L ) and the contact angle (θ _PTFE ) of the engine oil on the surface of the fluororesin for the three engine oils are summarized in Table 1 and FIG. 5 , and are shown.

engine oil density
[g/m ³ ] kinematic viscosity
[cSt] total surface energy
(γ _L ) [mN/m] on the surface of the fluororesin
Contact angle (θ _PTFE )[°] 0w16 0.839 27.6 29.9±0.09 56.3±3.1 5w30 0.845 60.8 30.5±0.31 59.7±2.7 10w60 0.836 151 30.1±0.29 61.7±3.6

Table 1 shows the measurement results of the total surface energy (γ _L ) and the contact angle (θ _PTFE ) of the engine oil on the fluororesin surface for three engine oils, and FIG. 5 is the engine oil on the fluororesin surface for the three engine oils. It is a graph showing the measurement result of the contact angle (θ _PTFE ).

Referring to Table 1 and FIG. 5 , the total surface energy (γ _L ) of three engine oils having different viscosities was measured at a level similar to about 30 mN/m. And, as the viscosity of the engine oil increases, it can be seen that the contact angle (θ _PTFE ) of the engine oil on the surface of the fluororesin increases.

After that, by substituting the total surface energy (γ _L ) of the engine oil and the contact angle (θ _PTFE ) of the engine oil on the surface of the fluororesin into Equation 4, γ _LD = (γ _L (cosθ _PTFE +1)) ² /80 , the non-polar surface energy (γ _LD ) of engine oil was calculated.

After that, by substituting the total surface energy of the liquid (γ _L ) and the non-polar surface energy (γ _LD ) of the engine oil into Equation 2, γ _LP =γ _L -γ _LD , the polar surface energy of the engine oil (γ _LP ) was calculated.

The calculation results of the total surface energy (γ _L ), non-polar surface energy (γ _LD ), and polar surface energy (γ _LP ) for three engine oils are summarized in Tables 2 and 6 and shown.

engine oil kinematic viscosity
[cSt] total surface energy
(γ _L ) [mN/m] non-polar surface energy
(γ _LD ) [mN/m] Polar surface energy
(γ _LP ) [mN/m] 0w16 27.6 29.9 27.00 2.90 5w30 60.8 30.5 26.31 4.19 10w60 151 30.1 24.61 5.49

Table 2 shows the calculation results of total, non-polar, and polar surface energies (γ _L , γ _LD , γ _LP ) for three engine oils, and FIG. 6 shows total, non-polar and polar surface energies (γ _L ) for three engine oils. , γ _LD , γ _LP ) is a graph showing the calculation results.

Referring to Table 2 and FIG. 6 , it can be seen that in engine oil having a large viscosity, the ratio of the polar surface energy (γ _LP ) of the engine oil to the total surface energy (γ _L ) of the engine oil increases. Therefore, on a solid surface without non-polar surface energy (γ _SD ), such as a fluororesin, as the polar surface energy (γ _LP ) of the engine oil increases, the ratio of the non-polar surface energy (γ _LD ) of the engine oil decreases, thereby Due to this, the contact angle (θ _PTFE ) of the engine oil on the surface of the fluororesin increases.

(Experimental Example 2)

In Experimental Example 2, polar surface energy (γ _SP ) and non-polar surface energy (γ _SD ) for three metal samples (Steel, Si-DLC, CrN) were calculated.

First, for two liquids, water, and diiodomethane (DIM) whose polar surface energy (γ _L2P ) and non-polar surface energy (γ _L2D ) are known in advance, the contact angle of the liquid on the metal surface ( θ _S2 ) was measured, respectively.

Then, for two liquids, water and DIM, the contact angle of the liquid at the metal surface (θ _S2 ), the polar surface energy of the liquid (γ _L2P ), the non-polar surface energy of the liquid (γ _L2D ) and the total surface energy of the liquid Solve the simultaneous equations by substituting (γ _L2 ) into Equation 1, (γ _SD γ _L2D ) ^1/2 +(γ _SP γ _L2P ) ^1/2 =0.5γ _L2 (cosθ _S2 +1), respectively, and the polarity of the metal Surface energy (γ _SP ) and non-polar surface energy (γ _SD ) were calculated.

As a result of measuring the contact angle (θ _S2 ) of water and DIM on the metal surface for three metals, the calculation results of the non-polar surface energy (γ _SD ), polar surface energy (γ _SP ), and total surface energy (γ _S ) of the metal are Table 3, Fig. 7, Fig. 8 and Fig. 9 are summarized and shown.

metal Contact angle (θ _S2 )[°] surface energy [mN/m] water DIM Nonpolar (γ _SD ) Polarity (γ _SP ) Total (γ _S ) Steel 89.8 ±1.9 53.1±1.5 32.55 1.91 34.46 Si-DLC 73.8 ±4.9 43.6±3.3 37.73 6.24 43.98 CrN 98.8 ±3.8 52.2±2.9 33.03 0.32 33.34

Table 3 is the measurement result of the contact angle (θ _S2 ) of water and DIM on the metal surface for three types of metals, and the calculation results of total, non-polar and polar surface energies (γ _S , γ _SD , γ _SP ) for three types of metals . 7 is a graph showing the measurement result of the contact angle of water on the metal surface for three types of metals, FIG. 8 is a graph showing the measurement results of the contact angle of DIM on the metal surface for three types of metals, and FIG. It is a graph showing the calculation results of total, non-polar and polar surface energies (γ _S , γ _SD , γ _SP ).

Referring to Table 3, 7, 8 and 9, in the Si-DLC metal, the contact angle (θ _S2 ) of water and DIM on the metal surface is the smallest, and the total surface energy (γ _S ) of the metal is the largest. Able to know. (Si-DLC >> Steel > CrN) And, in Si-DLC metal, it can be seen that the difference between the ratio of the polar surface energy (γ _SP ) and the non-polar surface energy (γ _SD ) of the metal is the largest.

(Experimental Example 3)

In Experimental Example 3, the interaction between the engine oil and the metal interface was analyzed for three types of engine oil of Experimental Example 1 and three types of metals of Experimental Example 2.

First, using Equation 5, ΔG _SL =-2[(γ _SD γ _LD ) ^0.5 +(γ _SP γ _LP ) ^0.5 ], for three engine oils of Experimental Example 1 and three types of metals in Experimental Example 2, The Gibbs free energy (ΔG _SL ) of the interface was calculated.

The calculation results of the Gibbs free energy (ΔG _SL ) at the interface for three engine oils and three metals are summarized in Table 4 and shown.

interface cast
Free energy (ΔG _SL ) Steel Si-DLC CrN OW16 -64.3 -72.2 -62.0 5W30 -64.5 -73.1 -61.6 10W60 -63.4 -72.5 -60.1

Table 4 shows the calculation results of the Gibbs free energy (ΔG _SL ) of the interface for three engine oils and three metals.

After that, using Equation 6, Compatibility=abs(abs(ΔG _SL )-γ _L ), compatibility was calculated for three engine oils of Experimental Example 1 and three metals of Experimental Example 2. .

The calculation results of compatibility for three types of engine oil and three types of metals are summarized in Tables 5 and 10, and are shown.

compatibility Steel Si-DLC CrN OW16 34.4 42.3 32.1 5W30 34.0 42.6 31.1 10W60 33.4 42.4 30.0

Table 5 shows the results of calculating the suitability for 3 types of engine oil and 3 types of metals, and 10 is a graph showing the calculation results of the compatibility for 3 types of engine oil and 3 types of metals.

Referring to Table 5 and FIG. 10 , it can be seen that Si-DLC has the greatest suitability of metals for engine oil and CrN has the smallest. And, in the case of Si-DLC having a large polar surface energy (γ _SP ), the variation in compatibility for engine oil is small, and in the case of CrN having a small polar surface energy (γ _SP ), the variation in compatibility to engine oil is large. Able to know.

After that, the contact angles (θ _S ) of the two types of engine oil on the surfaces of the three types of metals were measured using a static method, respectively. The results of measuring the contact angles (θ _S ) of two types of engine oil on the surfaces of three types of metals are summarized in Table 6 and shown.

engine oil 0W16 10W60 metal Steel Si-DLC CrN Steel Si-DLC CrN contact angle (θ _S )
[°] 15±1.3 12±1.2 13±2.0 19±2.0 14±2.1 23±1.1

Table 6 shows the measurement results of contact angles (θ _S ) of two types of engine oil on the surfaces of three types of metals. Referring to Tables 5 and 6, the contact angle (θ _S ) of the engine oil is the lowest on the Si-DLC surface having the greatest suitability for engine oil. Therefore, it can be seen that the wettability of the engine oil to the Si-DLC metal surface is the best. On the other hand, it can be seen that the deviation of the contact angle (θ _S ) in the engine oil 10W60 having a relatively large polar surface energy (γ _LP ) is large.

In the method for analyzing the surface energy correlation between liquid and solid according to an embodiment of the present invention, the engine oil and the engine oil and Wettability of the engine oil to the metal surface by analyzing the interaction of the engine oil and metal interface by calculating the ratio of the polar and non-polar or dispersive components of the metal in contact has a predictable effect.

As described above, the present invention has a main technical idea to provide a method for analyzing the surface energy correlation between liquid and solid, and the embodiment described above with reference to the drawings is only one embodiment, and the true The scope of rights is based on the claims, but will also extend to equivalent embodiments that may exist in various ways.

Claims (4)

a first step of calculating the polar surface energy (γ _LP ) and non-polar surface energy (γ _LD ) of the liquid;
a second step of calculating the polar surface energy (γ _SP ) and the non-polar surface energy (γ _SD ) of the solid; and
A third step of analyzing the interaction of the liquid and solid interface; including,
The first step is
Step 1-1 measuring the total surface energy (γ _L ) of the liquid and the contact angle (θ _PTFE ) of the liquid on the fluororesin (PTFE) surface;
By substituting the total surface energy (γ _L ) of the liquid and the contact angle (θ _PTFE ) of the liquid on the surface of the fluororesin into the equation γ _LD =(γ _L (cosθ _PTFE +1)) ² /80, the non-polarity of the liquid Step 1-2 of calculating the surface energy (γ _LD ); and
Substituting the total surface energy (γ _L ) and the non-polar surface energy (γ _LD ) of the liquid into the equation γ _LP =γ _L -γ _LD , the polar surface energy (γ _LP ) of the liquid is calculated in 1-3 Step; Surface energy correlation analysis method of a liquid and a solid comprising a. delete The method of claim 1,
The second step is
a 2-1 step of measuring the contact angle (θ _S2 ) of the liquid on the solid surface, respectively, for two liquids for which the polar surface energy (γ _L2P ) and the non-polar surface energy (γ _L2D ) are known in advance; and
For the above two liquids, the polar surface energy (γ _L2P ), non-polar surface energy (γ _L2D ), total surface energy (γ _L2 ), and contact angle (θ _S2 ) of the liquid on the solid surface of the liquid are calculated by the equation (γ _SD γ _L2D ) ^1/2 +(γ _SP γ _L2P ) ^1/2 =0.5γ _L2 (cosθ _S2 +1) by substituting, respectively, the polar surface energy (γ _SP ) and the non-polar surface energy (γ _SD ) of the solid A method of analyzing the correlation between surface energy of a liquid and a solid, comprising: a second step of calculating; The method of claim 1,
The third step is
For the liquid in step 1 and the solid in step 2, using the formula ΔG _SL =-2[(γ _SD γ _LD ) ^0.5 +(γ _SP γ _LP ) ^0.5 ], the Gibbs free energy of the interface (ΔG _SL ) step 3-1 to calculate;
a 3-2 step of calculating compatibility of the solid surface reference as an absolute value of a value obtained by subtracting the surface energy of the liquid (γ _L ) from the absolute value of the Gibbs free energy (ΔG _SL ) of the interface;
a third step of measuring the contact angle (θ _S ) of the liquid on the solid surface; and
A method for analyzing the surface energy correlation between a liquid and a solid, comprising: a step 3-4 of comparing the suitability and the contact angle (θ _S ) of the liquid on the surface of the solid.

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