Patent Application
20240191387
This application claims the benefit of Chinese Patent Application No. CN202211603745.8 filed on Dec. 13, 2022, in the State Intellectual Property Office of China, the whole disclosure of which is incorporated herein by reference.
The present disclosure relates to electroplating field, more particularly to a coating structure comprising graphite alloy and a preparation method.
Various metal coatings are widely used on components for electronics, healthcare, locomotives, aviation, and navigation. With the rapid development of the performance of components, people have more demanding requirements for electrical conductivity, thermal conductivity, wear resistance, corrosion resistance, and solderability performances, etc., of the metal coatings. It has been found that using graphite alloy to manufacture coating can increase its lubricity and wear resistance, resulting in a lower friction coefficient with improved electrical conductivity, thermal conductivity, and wear resistance properties.
However, the non-polarity of the graphite makes it non-hydrophilic. As a result, during the preparation process of graphite alloy, it is easy for graphite to separate and precipitate. This results in an uneven distribution of graphite in the coating. Graphite is also prone to be distributed in the superficial layer of the coating, and adhesion of the coating decreases as the content of graphite increases. The deposition quality and efficiency of the coating are not high. Moreover, as graphite partially precipitates during the preparation process, free graphite dust can be harmful to human health. People who inhale it for a long time may suffer allergic asthma and dust-related diseases. Current methods for preparing graphite alloy also have other drawbacks, such as a narrow working window for plating solution, limited thickness of coating, and difficulty in industrial mass production.
According to an embodiment of the present disclosure, a coating structure includes a substrate, a first metal layer, a second alloy layer, a third metal layer, and a fourth alloy layer. The first metal layer is plated on an outside of the substrate and does not include graphite. The second alloy layer is plated on an outside of the first metal layer and is synthesized from graphite and metal. The third metal layer is plated on an outside of the second alloy layer and does not include graphite. The fourth alloy layer is plated on an outside of the third metal layer and is synthesized from graphite and metal.
The invention will now be described by way of example with reference to the accompanying Figures, of which:
Exemplary embodiments of the present disclosure will be described hereinafter in detail with reference to the attached drawings, wherein the like reference numerals refer to the like elements. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein; rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the disclosure to those skilled in the art.
In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.
The first metal layer 104 is plated on the outside of the substrate 102, and the first metal layer does not include graphite. The first metal layer 104 may be pure metal or alloy. The first metal layer 104 may include a single layer or multiple stacked layers of a silver layer, a gold layer, a tin layer, a platinum layer, a nickel layer, a palladium layer, a silver alloy layer (such as silver-tin alloy), a gold alloy layer (such as gold-cobalt alloy or gold-nickel alloy), a tin alloy layer, a platinum alloy layer, a nickel alloy layer (such as nickel-phosphorus alloy), and a palladium alloy layer (such as palladium-nickel alloy). For example, the first metal layer 104 may be a silver layer, a silver layer and a gold layer in a stack, or a silver layer and a silver-tin alloy layer in a stack.
A second alloy layer 106 is plated on the outside of the first metal layer 104, and the second alloy layer 106 includes an alloy synthesized from graphite and metal. The second alloy layer 106 includes a single layer or multiple stacked layers of an alloy layer synthesized from at least graphite and silver (such as silver graphite or silver-tin graphite), an alloy layer synthesized from at least graphite and gold (such as gold graphite or gold-cobalt graphite), an alloy layer synthesized from at least graphite and tin (such as tin graphite), an alloy layer synthesized from at least graphite and nickel (such as nickel graphite or palladium-nickel graphite), an alloy layer synthesized from at least graphite and palladium (such as silver-palladium graphite), an alloy layer synthesized from at least graphite and antimony, and an alloy layer synthesized from at least graphite and bismuth. For example, the second alloy layer 106 may be a silver-tin graphite layer, or a silver graphite layer and a tin graphite layer in a stack. The first metal layer 104 can provide a structure similar to the second alloy layer 106 for plating and reducing face tension, so that the second alloy layer 106 can be closely combined with the first metal layer 104. Compared to plating the second alloy layer 106 directly on the substrate 102, the arrangement of the first metal layer 104 can solve the problem of weak adhesive when the graphite alloy is combined directly with the substrate 102.
The third metal layer 108 is plated on the outside of the second alloy layer 106, and the third metal layer 108 does not include graphite. The arrangement of the third metal layer 108 is similar to that of the first metal layer 104. In particular, the third metal layer 108 may include a single layer or multiple stacked layers of a silver layer, a gold layer, a tin layer, a platinum layer, a nickel layer, a palladium layer, a silver alloy layer, a gold alloy layer, a tin alloy layer, a platinum alloy layer, a nickel alloy layer, and a palladium alloy layer.
The fourth alloy layer 110 is plated on the outside of the third metal layer 108, and the fourth alloy layer 110 includes an alloy synthesized from graphite and metal. The arrangement of the fourth alloy layer 110 is similar to that of the second alloy layer 106. In particular, the fourth alloy layer 110 may include a single layer or multiple stacked layers of an alloy layer synthesized from at least graphite and silver, an alloy layer synthesized from at least graphite and gold, an alloy layer synthesized from at least graphite and tin, an alloy layer synthesized from at least graphite and nickel, an alloy layer synthesized from at least graphite and palladium, an alloy layer synthesized from at least graphite and antimony, and an alloy layer synthesized from at least graphite and bismuth.
Optionally, the coating structure 100 may include a fifth metal layer 112. The fifth metal layer 112 is plated on the outside of the fourth alloy layer 110, and the fifth metal layer 112 does not include graphite. The arrangement of the fifth metal layer 112 is similar to that of the first metal layer 104. Optionally, the coating structure 100 may include a sixth alloy layer 114. The sixth alloy layer 114 is plated on the outside of the fifth metal layer 112, and the sixth alloy layer 114 includes an alloy synthesized from graphite and metal. The arrangement of the sixth alloy layer 114 is similar to that of the second alloy layer 106. Optionally, the coating structure 100 further includes a repeating stacked layer 116. The repeating stacked layer 116 includes a pair or multiple pairs of a metal and an alloy layers in a stack. For example, the repeating stacked layer 116 can include a pair of a metal and an alloy layers in a stack, wherein the arrangement of the metal layer is similar to that of the first metal layer 104, and the arrangement of the alloy layer is similar to that of the second alloy layer 106.
It should be noted that all the metal layers in the coating structure 100, namely the first metal layer 104, the third metal layer 108, the fifth metal layer 112, and the metal layers in the repeating stacked layer 116, may have the same or different structure and coating composition. Similarly, all the alloy layers in the coating structure 100, namely the second alloy layer 106, the fourth alloy layer 110, the sixth alloy layer 114, and the alloy layers in the repeating stacked layer 116, may have the same or different structure and coating composition. By arranging the metal layers without graphite and the alloy layers with graphite to be repeated in a stack, the coating structure 100 can be arranged to any desired thickness, meeting the requirements of practical applications. In addition, the metal layer without graphite can also serve as a sealing layer, especially in the case that the coating structure 100 wears, as it can prevent graphite particles within the coating from floating in the air, thereby avoiding hazards to human health.
Optionally, the coating structure 100 further includes a metal sealing layer 118. The metal sealing layer 118 is plated on the secondary outer side of the coating structure 100, which may be a silver layer, a tin layer, or a silver-tin alloy layer, for sealing the coating structure. Optionally, the coating structure 100 further includes an organic layer 120. The organic layer 120 is covered on the outermost side of the coating structure 100, which may be sealing agent or lubricating oil, etc.
Step S202: a first metal layer 104 is plated on the outside of the substrate 102, wherein the first metal layer 104 does not include graphite. In this embodiment, the first metal layer 104 is obtained by flash plating. In other embodiments, other metal plating techniques such as chemical plating and hot dipping can also be used to obtain the first metal layer 104.
Step S204: colloid including graphite is mixed with electroplating solution including second metal ions. In particular, graphite particles are added to colloid including Sn2+ and Pd2+ and well stirred, to obtain the colloid including graphite. For example, an acidic colloidal solution of stannous chloride and palladium chloride is firstly prepared, and then anionic dispersant such as sodium hexametaphosphate or sodium stannate is added to mix with the solution to obtain a homogeneous and stable colloid. Alternatively, Sn2+ is added to colloid palladium, wherein the concentrations of Sn2+ and Pd2+ are adjusted. Then, micro- or nano-sized graphite is added to the colloid and stirred thoroughly to obtain the colloid including graphite. To obtain the second alloy layer 106 of silver-tin graphite, this embodiment mixes the colloid including graphite with an electroplating solution including second metal ions (namely Ag+ and Sn2+). In other example, in order to obtain other types of graphite alloys, the colloid including graphite is mixed with an electroplating solution containing other second metal ions (such as gold ions, nickel ions, etc.)
Step S206: the mixed electroplating solution including the second metal ions is used to be electrodeposited on the outside of the first metal layer 104, to obtain a second alloy layer 106 synthesized from graphite and the second metal. During the process of electrodeposition, the second metal ions (namely Ag+ and Sn2+) and graphite are deposited together on the outside of the first metal layer 104, thereby obtaining the second alloy layer 106 of silver-tin graphite.
Step S208: ultrasonic water cleaning is used to remove graphite particles on the surface of the second alloy layer 106.
Optionally, the embodiment continues to perform step S210 such that a third metal layer 108 is plated on the outside of the second alloy layer 106, wherein the third metal layer 108 does not include graphite. The execution of this step can be referred to step S202. Likewise, the embodiment may continue to perform step S212 such that colloid including graphite is mixed with electroplating solution including fourth metal ions. The execution of this step can be referred to step S204. The embodiment may continue to perform step S214 such that the mixed electroplating solution including the fourth metal ions is used to be electrodeposited on the outside of the third metal layer 108, to obtain a fourth alloy layer 110 synthesized from graphite and the fourth metal. The execution of this step can be referred to step S206. The embodiment may also continue to perform step S216 such that ultrasonic water cleaning is used to remove graphite particles on a surface of the fourth alloy layer 110. The execution of this step can be referred to step S208. Optionally, the embodiment performs steps S210˜S216 repeatedly.
Further, the embodiment performs step S218 such that a metal sealing layer 118 is plated on the secondary outer side of the coating structure 100. The embodiment performs step S220 that an organic layer 120 is covered on the outermost side of the coating structure 100.
After completing the preparation method above, the odd part can be taken out of the rack or the barren, or the roll of the continuous strip or the conveyor belt can be collected. In the preparation method above, metal and graphite are deposited together by utilizing graphite colloid, thereby obtaining graphite alloy. This method can be used to prepare the second alloy layer 106 including graphite alloy. The second alloy layer 106 may include a single layer or multiple stacked layers of an alloy layer synthesized from at least graphite and silver, an alloy layer synthesized from at least graphite and gold, an alloy layer synthesized from at least graphite and tin, an alloy layer synthesized from at least graphite and nickel, an alloy layer synthesized from at least graphite and palladium, an alloy layer synthesized from at least graphite and antimony, and an alloy layer synthesized from at least graphite and bismuth. The advantages of this method for preparing graphite alloy include a wide working window for the plating solution, high deposition efficiency, stable quality of the coating, and feasibility on industrial mass production. Additionally, in the preparation method above, the step of cleaning graphite particles can prevent people from easily contacting with graphite particles when using the coating structure.
In addition, those areas in which it is believed that those of ordinary skill in the art are familiar, have not been described herein in order not to unnecessarily obscure the invention described. Accordingly, it has to be understood that the invention is not to be limited by the specific illustrative embodiments, but only by the scope of the appended claims.
It should be appreciated for those skilled in this art that the above embodiments are intended to be illustrated, and not restrictive. For example, many modifications may be made to the above embodiments by those skilled in this art, and various features described in different embodiments may be freely combined with each other without conflicting in configuration or principle.
Although several exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that various changes or modifications may be made in these embodiments without departing from the principles and spirit of the disclosure, the scope of which is defined in the claims and their equivalents.
As used herein, an element recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of the elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202211603745.8 | Dec 2022 | CN | national |
