阅读说明：本技术 一种无微纳结构光滑疏水表面的制备方法 (Preparation method of smooth hydrophobic surface without micro-nano structure ) 是由 吕凤勇 林思帆 苗洁 邹积明 聂寒璐 董振标 李腊圆 季恺康 于淼 于 2021-09-26 设计创作，主要内容包括：本发明提供了一种无微纳结构光滑疏水表面的制备方法,涉及强化珠状冷凝的疏水表面制备技术领域,本发明的方法包括以下步骤：步骤1、将试样依次用丙酮、乙醇和盐酸超声波清洗,并用氮气吹干；步骤2、将步骤1中处理过的所述试样在第一温度下恒温热处理,得到无微纳结构的光滑疏水表面。本发明制备的光滑疏水表面能够降低液滴与表面之间的粘附力,有利于液滴发生迁移运动从而清扫沿途的小液滴,更新冷凝表面,强化冷凝换热性能；而且这种光滑疏水表面不存在微纳结构,表面的耐久性增强；此外,本发明加工工艺简单、成本低廉、耐久性好,绿色环保,具有有益的技术效果。(The invention provides a preparation method of a smooth hydrophobic surface without a micro-nano structure, and relates to the technical field of preparation of hydrophobic surfaces for strengthening bead-shaped condensation, wherein the preparation method comprises the following steps: step 1, ultrasonically cleaning a sample by using acetone, ethanol and hydrochloric acid in sequence, and drying the sample by using nitrogen; and 2, carrying out constant-temperature heat treatment on the sample processed in the step 1 at a first temperature to obtain a smooth hydrophobic surface without a micro-nano structure. The smooth hydrophobic surface prepared by the invention can reduce the adhesive force between the liquid drops and the surface, is beneficial to the liquid drops to move so as to clean the liquid drops along the way, renew the condensation surface and strengthen the condensation heat exchange performance; moreover, the smooth hydrophobic surface has no micro-nano structure, so that the durability of the surface is enhanced; in addition, the invention has the advantages of simple processing technology, low cost, good durability, environmental protection and beneficial technical effect.)

1. A preparation method of a smooth hydrophobic surface without a micro-nano structure is characterized by comprising the following steps:

step 1, ultrasonically cleaning a sample by using acetone, ethanol, hydrochloric acid and distilled water in sequence, and drying by using nitrogen;

and 2, carrying out constant-temperature heat treatment on the sample processed in the step 1 at a first temperature to obtain a smooth hydrophobic surface without a micro-nano structure.

2. The method for preparing the smooth hydrophobic surface without the micro-nano structure according to claim 1, wherein the first temperature in the step 2 is 150-200 ℃.

3. The method for preparing the smooth hydrophobic surface without the micro-nano structure according to claim 2, wherein the constant temperature heat treatment time in the step 2 is 60-120 min.

4. The method for preparing the micro-nano structure-free smooth hydrophobic surface according to claim 1, wherein the material of the sample is red copper.

5. The method for preparing the micro-nano structure-free smooth hydrophobic surface according to claim 4, wherein the sample is a flat plate.

6. The method for preparing the micro-nano structure-free smooth hydrophobic surface according to claim 4, wherein the sample is a round tube.

7. The method for preparing a smooth hydrophobic surface without micro-nano structure according to claim 6, wherein the circular tube is a light pipe.

8. The method for preparing the smooth hydrophobic surface without the micro-nano structure according to claim 6, wherein the round tube is a threaded tube.

9. The method for preparing the smooth hydrophobic surface without the micro-nano structure according to claim 8, wherein the outer wall surface of the threaded pipe is provided with annular threads.

10. The method for preparing the smooth hydrophobic surface without the micro-nano structure according to claim 9, wherein the cross-sectional shape, helix angle, thread height and pitch of the annular thread are combined at will.

Technical Field

The invention relates to the technical field of preparation of hydrophobic surfaces for strengthening bead-shaped condensation, in particular to a preparation method of a smooth hydrophobic surface without a micro-nano structure.

Background

The steam condensation phase-change heat exchange process is widely applied to the fields of refrigeration, petrochemical industry, aerospace and the like, and the strengthening of the condensation heat exchange process has important significance for energy conservation. The state of the vapor condensed on the solid surface can be classified into bead condensation and film condensation according to the wettability of the solid surface. When the beads are condensed, discrete condensed liquid drops are formed on the surface; in film-like condensation, a continuous liquid film covers the condensation surface, and the latent heat of phase change released by condensation must pass through the liquid film to be transferred to the condensation surface. The results of the study show that the thermal resistance of film-like coagulation is an order of magnitude greater than bead coagulation. Therefore, maintaining a continuously stable bead-like condensation state is particularly important for enhancing the condensate phase transition heat transfer performance.

At present, the phase change heat exchange of the enhanced condensation mainly has two modes: firstly, the condensation heat transfer surface is modified, namely a micro-nano structure is prepared on the surface and then a hydrophobic substance is modified to improve the hydrophobicity of the surface, so that higher periodic condensation nucleation number density is maintained, and the purpose of improving the condensation heat exchange performance is achieved; however, the micro-nano structure on the surface is often very fragile, so that the durability of the micro-nano structure is poor, and the micro-nano structure is easy to lose efficacy, so that the high condensation heat exchange capacity cannot be maintained for a long time. And secondly, the macroscopic structure of the outer wall surface of the heat transfer pipe is changed, so that the condensation heat exchange area is increased, a transport channel is provided for condensed liquid drops, and the liquid drops are promoted to be separated from the condensation surface. In order to enhance the phase change heat exchange performance of vapor condensation, researchers prepare hydrophobic or super-hydrophobic surfaces by a deposition method, a spin-coating method, an etching method and the like, but the methods need various instruments and equipment in the actual preparation process, are complex in process, high in cost, even cause environmental pollution, and are not beneficial to large-scale production and further popularization and application.

Therefore, the invention provides a preparation method of a smooth hydrophobic surface without a micro-nano structure, which has the advantages of simple preparation process, low cost, good durability and capability of maintaining efficient condensation heat exchange performance.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a preparation method of a smooth hydrophobic surface without a micro-nano structure.

The invention provides a preparation method of a smooth hydrophobic surface without a micro-nano structure, which comprises the following steps:

step 1, ultrasonically cleaning a sample by using acetone, ethanol, hydrochloric acid and distilled water in sequence, and drying by using nitrogen;

and 2, carrying out constant-temperature heat treatment on the sample processed in the step 1 at a first temperature to obtain a smooth hydrophobic surface without a micro-nano structure.

Preferably, the first temperature in step 2 is 150-.

Preferably, the constant temperature heat treatment time in the step 2 is 60-120 min.

Preferably, the material of the sample is red copper.

According to the scheme, firstly, impurities such as organic matters and oxides remaining on the surface of the sample are removed, then the sample is subjected to heat treatment to form a cuprous oxide surface, and therefore the smooth hydrophobic surface without the micro-nano structure is obtained. The smooth hydrophobic surface has better durability, and can effectively promote steam condensation nucleation, liquid drop combination and separation, clean liquid drops along the way and update the condensation surface, thereby reducing the heat resistance of condensation heat exchange, increasing the effective condensation heat exchange area and strengthening the condensation heat exchange performance.

Preferably, the sample is a flat plate.

Preferably, the sample is a round tube.

In the present invention, the sample may be a tube having another shape.

Preferably, the circular tube is a light pipe.

In the scheme, the light pipe has no macrostructure on the surface.

Preferably, the round tube is a threaded tube.

Further, the outer wall surface of the threaded pipe is provided with annular threads.

In the scheme, the outer wall surface of the threaded pipe is provided with an annular threaded structure, a space formed between adjacent threads forms a threaded groove for directional transportation, the surface of the sample is a smooth hydrophobic surface without a micro-nano structure, and the sample can be obtained through one-time heat treatment.

Further, the cross-sectional shape, helix angle, thread height and pitch of the annular thread may be any combination.

Compared with the prior art, the invention has the following beneficial effects:

1. compared with the conventional surface, the preparation method of the smooth hydrophobic surface without the micro-nano structure has the advantages that the smooth hydrophobic surface has no micro-nano structure, the viscous force between the liquid drops and the surface is reduced, the liquid drops are not easy to pin on the surface, the micro-liquid drops are favorable for migration movement, the liquid drops along the way are cleaned, the condensation area is provided for secondary condensation nucleation, the condensation nucleation process is accelerated, the condensation heat exchange thermal resistance is weakened, and the condensation heat exchange capacity is obviously enhanced.

2. The preparation method of the smooth hydrophobic surface without the micro-nano structure, provided by the invention, can be used for preparing the original surface into the smooth hydrophobic surface only by carrying out one-time heating treatment, has the advantages of simple processing technology, low cost, environmental friendliness, simple equipment requirement and good durability, and can be completed under general conditions.

3. According to the preparation method of the smooth hydrophobic surface without the micro-nano structure, the thread structure not only increases the condensation heat exchange area, but also provides a directional transport channel for condensed liquid drops, so that the liquid drops are favorable for migration movement, and the merging and directional transport of the condensed liquid drops are promoted.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a photo of a smooth hydrophobic red copper round tube without a micro-nano structure in example 1 of the present invention;

FIG. 2 is a photograph of a smooth, hydrophobic round copper tube with a threaded structure according to example 2 of the present invention;

FIG. 3 is a contact angle of a smooth hydrophobic surface according to an embodiment of the present invention;

FIG. 4 is an SEM photograph of a smooth hydrophobic surface of an embodiment of the present invention;

FIG. 5 is an XPS spectrum of the chemical composition of a smooth hydrophobic surface and a pristine surface of an example of the present invention;

fig. 6A, 6B, 6C are photographs of the microscopic condensation droplet formation, polymerization, detachment and droplet reformation processes on the smooth hydrophobic surface of example 1 of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

The invention provides the preparation method of the smooth hydrophobic surface without the micro-nano structure, which has the advantages of simple and convenient process, simple equipment requirement, low cost, environmental protection and large-scale production. The smooth hydrophobic surface prepared by the method has better durability, and the condensed liquid drops are not easy to pin on the smooth hydrophobic surface, so that the condensed liquid drops are favorable for being migrated and cleaning small liquid drops on the path, the condensed heat exchange surface is updated, the effective condensed heat exchange area is increased, and the condensed heat exchange performance is enhanced.

The material of the sample selected by the invention is red copper, the sample is a flat plate or a round tube, and can also be a pipeline with other shapes, and correspondingly, the surface of the sample is a plane or a curved surface. The round tube can be a light tube without a macroscopic structure or a threaded tube. The outer wall surface of the threaded pipe is provided with an annular thread structure, and the cross section shape, the helix angle, the thread height and the distance of the annular thread can be combined at will.

The preparation method of the smooth hydrophobic surface without the micro-nano structure comprises the following steps:

step 1, ultrasonically cleaning a sample by using acetone, ethanol, hydrochloric acid and distilled water in sequence, and drying by using nitrogen;

and 2, carrying out constant-temperature heat treatment on the sample processed in the step 1 at a first temperature to obtain a smooth hydrophobic surface without a micro-nano structure.

In the invention, the first temperature of the step 2 is 150-.

Example 1

A preparation method of a smooth hydrophobic surface without a micro-nano structure comprises the following steps:

step 1, sample pretreatment

Selecting a round red copper tube with the outer diameter of 8mm and the inner diameter of 4mm as a sample, and sequentially ultrasonically cleaning the round red copper tube for 10-15min by using acetone and ethanol, and then cleaning the round red copper tube by using distilled water; and then soaking in a hydrochloric acid solution with the concentration of 5 wt% for 10-20min, finally cleaning with distilled water and quickly drying with nitrogen, thereby removing impurities such as organic matters, oxides and the like on the surface of the round red copper tube and obtaining a clean round red copper tube.

Step 2, performing hydrophobic treatment on the outer surface of the sample

And (2) putting the round red copper tube pretreated in the step (1) into an oven, carrying out constant-temperature heat treatment at 150 ℃ for 60min, and then naturally cooling to room temperature to finally obtain the round red copper tube with a smooth and hydrophobic surface, wherein the round red copper tube is shown in figure 1.

The contact angle of the round red copper tube obtained by the above process is 114.4 ° ± 0.8 °, and the round red copper tube is hydrophobic, as shown in fig. 3. The hydrophobic surface obtained after heat treatment has no micro-nano structure except a few natural pits, and the whole surface is almost in a smooth state, as shown in fig. 4. By characterizing the chemical composition of the smooth hydrophobic surface, as shown in FIG. 5, it was found that surface Cu after heating⁺/Cu²⁺Increases the atomic ratio of (a) from 0.82 to 1 of the heated front surface493 (for a smooth hydrophobic surface after heat treatment, four peaks with binding energies of 962.79eV, 944.18eV and 952.79eV, 933.01eV correspond to Cu, respectively²⁺And Cu⁺(ii) a And four peaks with binding energies of 961.92eV, 943.67eV and 952.53eV, 932.73eV respectively correspond to Cu of the heating front surface²⁺And Cu⁺) Superficial cuprous oxide (Cu)₂O) exhibits hydrophobicity, which indicates that the surface forms a cuprous oxide hydrophobic surface after heat treatment. 6A, 6B and 6C show the processes of condensation nucleation of steam on a smooth hydrophobic surface, liquid drop aggregation and combination, migration movement, re-nucleation and the like, and the processes further enhance the bead-shaped condensation heat exchange performance. Experimental research shows that the condensation heat exchange coefficient of the smooth hydrophobic red copper round tube is 1.5-1.8 times that of the original microstructure red copper tube.

Example 2

The present embodiment is completely the same as the sample pretreatment and the sample outer surface hydrophobic treatment processes of example 1, except that the present embodiment selects a red copper round tube with an outer diameter of 8mm and an inner diameter of 4mm as the sample, and processes an annular thread with a thread pitch of 1.0mm and a thread angle of 60 ° on the outer tube wall of the red copper round tube by a thread tapping process, wherein the thread height is 0.650mm, the thread root thickness is 0.833mm, the thread top thickness is 0.125mm, and the thread root groove width is 0.167mm, and the sample is shown in fig. 2.

The smooth hydrophobic red copper pipe of this embodiment uses helicitic texture to increase condensation heat transfer area, and the screw thread side is favorable to the liquid drop migration motion, and the condensation heat transfer coefficient further improves.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.