Preparation method of high-purity titanium nitride coating with conductive and corrosion-resistant functions
By preparing a high-purity titanium nitride coating on the metal bipolar plate of a fuel cell, the problem of increased contact resistance caused by titanium surface enrichment was solved, thereby improving the conductivity stability of the coating and the performance of the fuel cell stack.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-03-27
AI Technical Summary
In the prior art, titanium nitride coatings exhibit titanium surface enrichment on the metal bipolar plates of fuel cells, leading to increased contact resistance and affecting stack performance and lifespan.
Titanium nitride coatings were prepared using PVD. The titanium nitride content in the coating was controlled by combining plasma etching and nitrogen ionization. The nitrogen ionization efficiency was improved by introducing a coil magnetic field, thereby eliminating the enrichment effect on the titanium surface.
This improved the electrical conductivity stability of the coating, reduced contact resistance, and extended the lifespan of the fuel cell.
Smart Images
Figure CN121737631A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vacuum coating preparation technology, and in particular to a method for preparing a conductive and corrosion-resistant titanium nitride coating for metal bipolar plates of fuel cells. Background Technology
[0002] Metal bipolar plates in fuel cells play crucial roles in conducting current and separating the fuel between the anode and cathode. Especially in current conduction, the plates require excellent conductivity and stability. However, metal bipolar plates are highly susceptible to electrochemical corrosion in electrochemical environments, thus affecting battery life. A common approach to address this issue is to form a conductive and corrosion-resistant coating on the surface of the metal bipolar plates through surface treatment to slow down the corrosion process. Titanium nitride coating is a relatively common material. However, during PVD deposition, titanium accumulates on the surface, resulting in a relatively low proportion of titanium nitride structures in the surface coating. This leads to rapid passivation of the surface layer during plate operation, causing a rapid increase in contact resistance and ultimately affecting the performance and lifespan of the fuel cell stack. Summary of the Invention
[0003] To address the above problems, this invention provides a method for preparing a high-purity titanium nitride coating that is both conductive and corrosion-resistant, comprising the following steps:
[0004] (1) Clean the substrate to remove impurities from the substrate;
[0005] (2) The titanium underlayer and titanium nitride coating were prepared by PVD. Nitrogen gas was introduced as the reaction gas during the preparation of the titanium nitride layer. The nitrogen flow rate was 30 sccm-300 sccm, the nitrogen / argon ratio was 1 / 10-1 / 1, the vacuum chamber pressure was 0.3 Pa-1 Pa, the substrate bias voltage was 100 V-450 V, the duty cycle was 10%-90%, and the deposition time was 10 min-120 min.
[0006] (3) Turn on the plasma source or filament ion source or other plasma power supply device that can generate a continuous plasma field, and perform plasma etching in an inert gas (such as argon) atmosphere for 30 min-60 min.
[0007] (4) Keep the plasma power supply device in the previous step in the open state, introduce nitrogen through the nitrogen gas pipeline, the nitrogen flow rate is 500sccm-2000sccm, fully ionize the nitrogen in the plasma atmosphere, the substrate bias voltage is 300V-450V, the duty cycle is 10%-90%, and maintain for 30min-120min.
[0008] The titanium nitride coating prepared by the above steps has a contact resistance of 3 mΩ∙cm under a clamping force of 1.2 MPa.2 -10mΩ∙cm 2 Corrosion current density: 0.01 μA / cm 2 -0.5μA / cm 2 The titanium nitride content of the coating surface is 80%-95%.
[0009] The beneficial effects of this invention are:
[0010] (1) This invention provides a method for preparing a high-purity titanium nitride coating, which reduces the passivation tendency of the coating and improves the contact resistance stability of the coating by controlling the content of titanium nitride on the coating surface.
[0011] (2) By introducing a coil magnetic field and a plasma source into the equipment, the ionization efficiency of nitrogen can be improved to a greater extent, the content of titanium nitride can be further increased, and the enrichment effect of the coated titanium surface can be eliminated. Attached Figure Description
[0012] Figure 1 , Figure 2 This is a schematic diagram of the plasma source device of the present invention.
[0013] In the diagram: 1. Magnetic field coil; 2. Vacuum chamber; 3. Plasma excitation source; 4. Nitrogen pipeline.
[0014] Figure 3 The figure shows the GID spectra of titanium nitride coatings prepared normally without the method of this invention at different incident angles, as well as the atomic percentage content of titanium nitride and titanium measured at each incident angle. This figure illustrates that the coating has the characteristic of titanium surface enrichment. Detailed Implementation
[0015] According to one embodiment of the present invention, it further includes:
[0016] (1) Clean the substrate to remove impurities from the substrate;
[0017] (2) The titanium underlayer and titanium nitride coating were prepared by PVD. Nitrogen gas was introduced as the reaction gas during the preparation of the titanium nitride layer. The nitrogen gas flow rate was 50 sccm, the argon gas flow rate was 300 sccm, the vacuum chamber pressure was 0.45 Pa, the substrate bias voltage was 300 V, the duty cycle was 30%, and the deposition time was 30 min.
[0018] (3) Turn on the plasma source and perform plasma etching in an argon atmosphere for 30 minutes;
[0019] (4) Keep the plasma power supply device in the previous step in the open state, introduce nitrogen through the nitrogen gas pipeline, the nitrogen flow rate is 1000 sccm, the vacuum chamber pressure is maintained at 1 Pa, fully ionize the nitrogen in the plasma atmosphere, the substrate bias voltage is 350 V, the duty cycle is 80%, and it is maintained for 60 min.
[0020] The titanium nitride coating prepared by the above steps has a contact resistance of 4.32 mΩ∙cm under a clamping force of 1.2 MPa. 2 Corrosion current density: 0.15 μA / cm 2 The titanium nitride content of the coating surface is 82.5%.
[0021] According to another embodiment of the present invention, it further includes:
[0022] (1) Clean the substrate to remove impurities from the substrate;
[0023] (2) The titanium underlayer and titanium nitride coating were prepared by PVD. Nitrogen gas was introduced as the reaction gas during the preparation of the titanium nitride layer. The nitrogen gas flow rate was 100 sccm, the argon gas flow rate was 400 sccm, the vacuum chamber pressure was 0.48 Pa, the substrate bias voltage was 260 V, the duty cycle was 40%, and the deposition time was 45 min.
[0024] (3) Turn on the plasma source and perform plasma etching in an argon atmosphere for 40 minutes;
[0025] (4) Keep the plasma power supply device in the previous step in the open state, introduce nitrogen through the nitrogen gas pipeline, the nitrogen flow rate is 800 sccm, the vacuum chamber pressure is maintained at 0.8 Pa, fully ionize the nitrogen in the plasma atmosphere, the substrate bias voltage is 300 V, the duty cycle is 35%, and it is maintained for 80 min.
[0026] The titanium nitride coating prepared by the above steps has a contact resistance of 5.44 mΩ∙cm under a clamping force of 1.2 MPa. 2 Corrosion current density: 0.11 μA / cm 2 The titanium nitride content of the coating surface is 85.2%.
[0027] According to another embodiment of the present invention, it further includes:
[0028] (1) Clean the substrate to remove impurities from the substrate;
[0029] (2) The titanium underlayer and titanium nitride coating were prepared by PVD. Nitrogen gas was introduced as the reaction gas during the preparation of the titanium nitride layer. The nitrogen gas flow rate was 300 sccm, the argon gas flow rate was 500 sccm, the vacuum chamber pressure was 0.52 Pa, the substrate bias voltage was 450 V, the duty cycle was 35%, and the deposition time was 60 min.
[0030] (3) Turn on the plasma source and perform plasma etching in an argon atmosphere for 60 minutes;
[0031] (4) Keep the plasma power supply device in the previous step in the open state, introduce nitrogen through the nitrogen gas pipeline, the nitrogen flow rate is 2000 sccm, the vacuum chamber pressure is maintained at 2 Pa, fully ionize the nitrogen in the plasma atmosphere, the substrate bias voltage is 350 V, the duty cycle is 60%, and it is maintained for 120 min.
[0032] The titanium nitride coating prepared by the above steps has a contact resistance of 7.34 mΩ∙cm under a clamping force of 1.2 MPa. 2 Corrosion current density: 0.052 μA / cm 2 The titanium nitride content of the coating surface is 92.1%.
[0033] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.
Claims
1. A method for preparing a high-purity titanium nitride coating with both conductive and corrosion-resistant properties, characterized in that, This coating is prepared by physical vapor deposition, using titanium, tantalum, or their alloys as the target material and 99.999% pure nitrogen as the reaction gas. The coating can be prepared on materials such as 316LSS, 304SS stainless steel, TA1 titanium, or silicon wafers, and includes the following steps: (1) Clean the substrate to remove impurities from the substrate; (2) The titanium underlayer and titanium nitride coating were prepared by PVD. Nitrogen gas was introduced as the reaction gas during the preparation of the titanium nitride layer. The nitrogen flow rate was 30 sccm-300 sccm, the nitrogen / argon ratio was 1 / 10-1 / 1, the vacuum chamber pressure was 0.3 Pa-1 Pa, the substrate bias voltage was 100 V-450 V, the duty cycle was 10%-90%, and the deposition time was 10 min-120 min. (3) Turn on the plasma source or filament ion source or other plasma power supply device that can generate a continuous plasma field, and carry out plasma etching in an inert gas (such as argon) atmosphere for 30-60 minutes. (4) Keep the plasma power supply device in the previous step in the open state, introduce nitrogen through the nitrogen gas pipeline, the nitrogen flow rate is 500sccm-2000sccm, fully ionize the nitrogen in the plasma atmosphere, the substrate bias voltage is 300V-450V, the duty cycle is 10%-90%, and maintain for 30min-120min.
2. The titanium nitride coating prepared by the method described in step (2) of claim 1, characterized in that: The prepared titanium nitride coating has the characteristic that the percentage of titanium nitride atoms in the coating structure is smaller the closer it is to the substrate. The titanium nitride content varies from 10% to 90%, and the titanium nitride has a face-centered cubic structure.
3. The plasma power supply device according to claim 1 has its excitation source located near the nitrogen gas inlet, and the excitation source is a ring or rectangular ring-shaped metal, the size of which needs to be adjusted according to the size and shape of the product, and a voltage of 1000V-3000V can be applied to the ring or rectangular ring-shaped metal.
4. The plasma power supply device according to claim 3 is further provided with an electromagnetic coil, which generates a magnetic field of 5mT-100mT. The electromagnetic coil is wound with enameled wire with a wire diameter of 1mm-3mm and a current of 1A-5A.
5. The nitrogen pipeline according to claim 1 has an H-shaped structure, with the main gas pipeline in the middle and branch pipes on both sides. Micro-holes with a size of 0.5mm-1mm are opened on the branch pipes, and the spacing between the holes is 2cm-5cm.