NL2031516A - High-thickness curved dlc product and preparation method and application thereof - Google Patents

Abstract

The present invention discloses a high-thickness curved DLC product and a preparation method and application thereof. The preparation method includes the following steps: step 81, placing substrates into a PVD furnace, turning on the power of a graphite target source and an ion source, applying a deposition bias voltage of gradient increase from -100 V to -10 V, 10 adjusting a current of gradient decrease from 10 A to 3 A, a deposition time being from 50 hours to 90 hours, and obtaining a DLC layer containing substrates, and step SZ, corroding the DLC layer obtained in step Sl to remove the substrates, thereby obtaining the high-thickness curved DLC products. The high-thickness curved DLC products are without the phenomenon such as cracking and desquamation. 15 Fig. l

Description

HIGH-THICKNESS CURVED DLC PRODUCT AND PREPARATION METHOD AND APPLICATION THEREOF

TECHNICAL FIELD The present invention relates to the technical field of diamond-like carbon (DLC), and more specifically relates to a high-thickness curved DLC product and a preparation method and its application.

BACKGROUND Heat exchanger is of great importance in industrial application, and heat-conducting components of the heat exchanger are generally made of copper alloys. Compared with the copper alloys, the diamond has a heat conductivity coefficient 6 times that of copper alloys, and therefore the heat exchanger made of diamond has an excellent heat conducting efficiency. However, the diamond heat exchanger is difficult to be manufactured due to the nature hardness and brittleness of the diamond. At present, the diamond-like carbon (DLC) film deposited by physical vapor deposition (PVD) technology has been widely used as anti-attrition material for auto parts as a result of its high hardness and high heat conductivity, being as one of ideal materials for heat exchange components. However, the PVD technology can only prepare the diamond-like carbon film with few microns to tens of microns in thickness, and cannot prepare directly DLCs with relatively high thickness because of the difficulty of preparing ultra-thick DLCs. The thicker the DLC, the greater the internal stress (being up to 10 GPa). Furthermore, when preparing a curve-shaped DLC product, the internal stress would rise rapidly, resulting in cracking and desquamation of DLC due to the effect of high stress. For example, the Chinese patent (CN108070857A) discloses an ultra-thick DLC coating, but the thickness thereof is only up to 50 um, which is even in a plane structure.

SUMMARY In order to overcome the technical barrier of preparing high-thickness curved DLC products, the present invention provides a preparation method for high-thickness curved DLC products. Another objective of the present invention is to provide a high-thickness curved DLC product. Another objective of the present invention is to provide application of the DLC products. In order to realize the above objectives, technical solutions adopted by the present invention are as follows: A preparation method for high-thickness curved DLC products, includes the following steps: step S1, placing substrates into a PVD furnace, turning on the power of graphite target sources and 10n sources, applying a deposition bias voltage of gradient increase from -10 V to -100 V; adjusting a current of gradient decrease from 10 A to 3 A; a deposition time being from 50 hours to 90 hours, and obtaining a DLC product containing substrates; and step S2, corroding the DLC layer containing substrates obtained in step S1 to remove the substrates, thereby obtaining the high-thickness curved DLC products.

At present in the existing technology, DLC films with a thickness of a few microns to tens of microns can be prepared by using PVD technology. With the thickness increasing, the internal stress of the DLC films increases, being likely to crack and desquamate. Especially in the case of preparing curved DLCs, the internal stress thereof is greater than that of planar films which is more likely to crack. It is found by the inventor through abundant experiments that adjusting negative bias voltage, current and time can greatly reduce the internal stress; a deposition bias voltage of gradient increase from -10V to -100V is applied; the deposition time is 50 hours to 90 hours; current is adjusted to decrease from 10 A to 3 A in gradient; at the early stage, by adjusting low bias voltage and high current, the internal stress of the initial DLC layer is relatively small and the adhesion degree is high, while a deposition rate can be guaranteed. High adhesion degree can prevent the DLC layers from cracking from each other. Finally, by removing the substrates, the high-thickness curved DLC products are obtained. Preferably, in step S1, in the condition of -10 V — -20 V and 8 A — 10 A, deposition lasts for 15 hours to 20 hours; in the condition of -25 V—-50 V and 5 A — 7 A, deposition lasts for 6 hours to 10 hours; in the condition of -60 V — -100 V and 3 A — 4 A, deposition lasts for 1 hour to 4 hours. The preparation method of the present invention can be applied to planar substrates and curved substrates, for example, substrates in pipe shape or bar shape. Preferably, the substrates are macromolecule substrates or metal alloy substrates. More preferably, the metal alloy substrates include but not limited to steel, copper alloy and aluminum alloy. Preferably, the high-thickness curved DLC products are DLC pipes, the substrates are metal alloy pipes or metal alloy bars. The high-thickness curved DLC products include but not limited to DLC pipes, and can also be DLC products in other special shape. The DLC pipes with a thickness of 250 um or more can be prepared by the above-mentioned method, without the phenomenon such as cracking.

The thickness of the DLC pipes has a rather great influence on the internal stress, and preferably, the thickness of the DLC pipes is 2000 um or less. The corrosion is chemical corrosion or electrochemical corrosion.

Before placing the substrates into the PVD furnace, a cleaning treatment is required for the substrates, and preferably in step S1, sand blast, rust removal and oil removal are performed to surface of the substrates.

As an implementing solution, preferably in step S1, in the condition of -10 V and 10 A, deposition lasts for 20 hours; in the condition of -20 V and 9 A, deposition lasts for 15 hours; in the condition of -25 V and 8 A, deposition lasts for 10 hours; in the condition of -30 V and 6 A, deposition lasts for 8 hours; in the condition of -50 V and 5 A, deposition lasts for 6 hours; in the condition of -60 V and 4 A, deposition lasts for 4 hours; in the condition of -80 V and 3 A, deposition lasts for 2 hours; in the condition of -100 V and 3 A, deposition lasts for 1 hour. It is found by the inventors that even distribution of the graphite target sources around the substrates can obtain a DLC layer with uniform texture, and the deposition rate would increase also. Preferably in step Sl, a plurality of graphite target sources are distributed equidistantly and evenly around the substrates. Preferably, the corrosion in step S2 is an electrochemical corrosion, which is performed in a solution of hydrochloric acid and sodium chloride using the DLC layer containing substrates as an anode and immersing the anode into the solution. Preferably, the electrochemical corrosion has a voltage of 40 - 60 V and a current of 10 - 20 A. Preferably, temperature of the electrolytic corrosion is 50 - 70°C. A high-thickness curved DLC product, is prepared by any of the above-mentioned methods. Application of the DLC products in preparing products of heat exchanger and radiator.

The products of heat exchanger and radiator prepared by the DLC products have strong plasticity and high heat conductivity coefficient. Compared with the prior art, the beneficial effects of the present invention is as follows: 5 In the preparation method for high-thickness curved DLC products provided by the present invention, by adjusting the deposition bias voltage, current and time, the internal stress can be greatly reduced. A deposition bias voltage of gradient increase from -10 V to -100 V is applied; the deposition time is reduced from 20 hours to 1 hour in gradient; current is adjusted to decrease from 10 A to 3 A in gradient, at the early stage, by adjusting low bias voltage and high current, the internal stress of the initial DLC layer is relatively small and the adhesion degree is high, while a deposition rate can be guaranteed. High adhesion degree can prevent the DLC layers from cracking from each other, and thus the high-thickness curved DLC products are obtained.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows a photograph of DLC pipes prepared in Example 1. FIG. 2 shows a photograph of a DLC pipe prepared in Comparative Example 1.

DETAILED DESCRIPTION Technical solutions of the examples in the present invention are clearly and completely described below, but the implementation of the present invention is not limited thereto.

Unless specitied, reagents, methods and equipment used in the present invention are all common reagents, methods and equipment in the art.

Example 1 Step S1, cleaned metal pipes or metal bars were placed in a PVD furnace which was sealed and vacuumized to 1X 107Pa, power of graphite target sources and ion sources was turned on, a negative bias voltage was applied according to the following sequence: deposition was performed for 20 hours at -10V, 10A; deposition was performed for 15 hours at -20V, 9A; deposition was performed for 10 hours at -25V, 8A; deposition was performed for 8 hours at -30V, 6A; deposition was performed for 6 hours at -50V, 5A; deposition was performed for 4 hours at -60V, 4A; deposition was performed for 2 hours at -80V, 3A; deposition was performed for 1 hour at -100V, 3A; and metal pipes containing DLC layers or metal bars containing DLC layers were obtained.

Step S2, products obtained in step S1 were subjected to electrolytic corrosion until the metal pipes or metal bars were corroded completely, thereby obtaining DLC pipes; the corrosion condition was as follows: current was 10 A, corrosion temperature was 65°C, and a corrosive liquid was 10 vol% NaCl solution after mixing. A thickness of the DLC pipes is 880 um. It can be seen from FIG. 1 that there’s no cracking in the DLC pipes.

Example 2 The preparation method of Example 2 was the same as that of Example 1, and the differences lay in that, the deposition bias voltage and deposition time were adjusted according to the following sequence: deposition was performed for 21 hours at a substrate negative bias voltage of -12 V; deposition was performed for 15 hours at -20 V; deposition was performed for 10 hours at -26 V; deposition was performed for 8 hours at -30 V; deposition was performed for 6 hours at -50 V; deposition was performed for 4 hours at -60 V; deposition was performed for 2 hours at -80 V; deposition was performed for 1 hour at -100 V; and the obtained DLC pipes had thickness of 480 um.

Example 3 The preparation method of Example 3 was the same as that of Example 1, and the differences lay in that, the deposition bias voltage and deposition time were adjusted according to the following sequence: deposition was performed for 15 hours at a substrate negative bias voltage of -10 V; deposition was performed for 12 hours at -15 V; deposition was performed for 10 hours at -20 V; deposition was performed for 6 hours at -30 V; deposition was performed for 5 hours at -50 V; deposition was performed for 4 hours at -60 V; deposition was performed for 3 hours at -80 V; deposition was performed for 2 hours at -100 V; and the obtained DLC pipes had thickness of 510 um.

It can be seen from Examples 1 - 3 that DLC pipes with different thickness can be obtained by adjusting the deposition bias voltage and deposition time.

Example 4 The preparation method of Example 4 was the same as that of Example 1, and the differences lay in that, the deposition bias voltage and deposition time were adjusted according to the following sequence: deposition was performed for 10 hours at a substrate negative bias voltage of -15 V; deposition was performed for 8 hours at -20 V; deposition was performed for 6 hours at -25 V; deposition was performed for 5 hours at -30 V; deposition was performed for 3 hours at -50 V; deposition was performed for 2 hours at -60 V; deposition was performed for 1 hour at -80 V, deposition was performed for | hour at -100 V; and the obtained DLC pipes had thickness of 260 um.

Comparative Example 1 The preparation method was the same as that of Example 1, and the differences lay in that, deposition was performed for 2 hours at a constant bias voltage of -60 V at 10 A to prepare DLC pipes.

It can be seen from FIG. 2 that a complete DLC pipe cannot be obtained, and the DLC layer desquamated at the metal surface.

Apparently, the above examples of the present invention are merely examples made to clearly illustrate the present invention, and make no limit to the implementation of the present invention.

Other different forms of variation or modification may also be made on the basis of the above description for a person of ordinary skill in the art.

It is unnecessary and impossible here to be exhaustive about all modes of implementation.

Any modifications, equivalent replacements and refinements, etc. made within the spirit and principles of the invention shall be included in the scope of the claims of the invention.

Claims (10)

CONCLUSIONS A preparation method for curved diamond-like carbon products (DLC) with high thickness, characterized in that the method comprises the following steps: step S1, placing substrates in a PVD furnace, turning on the power of the graphite target sources and ion sources applying a deviation voltage for bias voltage deposition from a gradient increase from -10 V to -100 V; adjusting a gradient decrease current from 10 A to 3 A; a total deposition time selected within a range of 50 hours to 90 hours, and obtaining a TLC layer containing substrates; and step S2, corroding the DLC layer containing substrates obtained in step S1 to remove the substrates, thereby obtaining the high-thickness curved DLC products. The production method for curved high-thickness DLC products according to claim 1, wherein in step S1, in the state of -10 V --20 V 8 A -- 10 A, the deposition takes 15 to 20 hours; in the condition of -25 V—-50 Ven5A-7 A, the deposition takes 6 to 10 hours; in the condition of -60 V—-100 Ven3 A—4 A, the deposition takes 1 to 4 hours. The production method for high thickness curved DLC products according to claim 1, wherein the substrates are macromolecular substrates or metal alloy substrates. The preparation method for high-thickness curved DLC products according to claim 1, wherein, before placing the substrates in the PVD oven in step S1, the surface of the substrates is sandblasted, derusted and deoiled. The production method for high-thickness curved DLC products according to claim 1, wherein the curved high-thickness DLC products are DLC tubes, the substrates are metal alloy tubes or rods. The production method for high-thickness curved DLC products according to claim 5, wherein in step S1, depositions are performed sequentially according to the following conditions: in the -10 V and 10 A condition, the deposition lasts for 20 hours; in the condition of -20 V and 9 A, the deposition takes 15 hours; in the condition of -25 V and 8 A, the deposition takes hours; in the condition of -30 V and 6 A, the deposition lasts for 8 hours; in the condition of -50 Ven 5 A, the deposition lasts for 6 hours; in the condition of -60 V and 4 A, the deposition takes 4 hours; in the condition of -80 V and 3 A, the deposition takes 2 hours; in the condition of -100 V and 3 A, the deposition takes 1 hour. 7. The preparation method for high thickness curved DLC products according to claim 5, wherein in step S2 a plurality of graphite target sources are equally spaced and evenly distributed around the substrates. The preparation method for curved high-thickness DLC products according to claim 5, the corroding is electrochemical corrosion. A high-thickness curved DLC product, characterized in that the product has been obtained by the preparation method according to any one of claims | through 8. Use of the high-thickness curved DLC products according to claim 9 in the manufacture of heat exchanger and radiator products.