Cathodic Cage Plasma Deposition of Ag/Porous Silicon as a Scalable Route To SERS Substrates

Titanium nitride (TiN) is a good choice for the improvement in surface hardness of high-speed steel. Unfortunately, it has low adhesion with substrate and exhibits high friction coefficient; as a result it does not provide sufficient protection against sliding wear in metal-to-metal contact. The adhesion problem can be removed by nitriding process, whereas friction coefficient can be reduced by solid lubrication coating. In this study, an attempt is made to synthesize TiN hard coating as well as solid lubrication coating of molybdenum disulfide (MoS2) using magnetron sputtering, along with substrate pre-treatment by cathodic cage plasma deposition using titanium cathodic cage. The cathodic cage plasma nitrided sample exhibits significantly higher surface hardness, which reduced by solid lubrication coating. The nitrided sample depicts the presence of iron nitrides, TiN and nitrogen diffused martensite phases, whereas coated samples shows the presence of MoS2 and TiN phases. The friction coefficient and machining temperature are dramatically reduced by lubrication coating. This study recommends that the use of cathodic cage plasma nitriding using titanium cathodic cage is beneficial for improved surface hardness, and addition of solid lubrication coating is beneficial for reducing the coefficient of friction and machining temperature by scarifying hardness. As, both the systems are already proven to be appropriate for industrial-scale uses, thus results from this study can be applied for industrial-scale application.

The fabrics with copper or copper oxide deposition are of considerable interest because of exceptional antibacterial properties, which are useable in medical, textiles, and hygiene applications. Unfortunately, the conventional techniques take long processing time, complex equipment, and combination of several processing steps (nanoparticles synthesis and their deposition on fabrics). In this novel study, cathodic cage plasma deposition assisted with copper cathodic cage is used for the synthesis of the copper oxide on polyester and polyamide fabrics. For the enhancement of synthesis efficiency, the effect of cathodic cage lid thickness is also investigated. The samples are assessed by using scanning electron microscopy, elemental dispersive spectroscopy, and X‐ray photoelectron spectroscopy. It is found that using cathodic cage plasma deposition, fabrics can be successfully synthesized by the copper oxide with comparatively small treatment time, cost‐effectively, and environmentally friendly. Interestingly, cathodic cage plasma treatment is already proved to be working effectively on industrial scale; thus, it is predicted to be of noteworthy importance for fabrics processing on large‐scale garments manufacturing and hospitals.

This review summarizes the development of cathodic cage plasma nitriding (CCPN) and cathodic cage plasma deposition (CCPD) techniques. CCPN was introduced to eliminate issues in direct current plasma nitriding (DCPN), such as the edge effect, by isolating the sample at a floating potential and using radiative heating. The process was further adapted for CCPD, in which the cage serves as a sputtering target (e.g., Ti, graphite, Mo, Hastelloy) for the deposition of ceramic and metallic films. Combining nitriding pretreatment with CCPD resulted in duplex treatments that establish a hardness gradient and enhance film adhesion. The most recent advance is cathodic cylinder plasma deposition (CCyPD), which employs compacted powder targets (such as MoS2 or metal oxides) for composite film deposition and in situ oxide reduction. The review traces the evolution from process improvement to a versatile platform for surface engineering.

In this study, a cathodic cage plasma deposition (CCPD) system equipped with a vanadium cathodic cage is used to deposit vanadium nitride coating on AISI-420 steel. This study aims to improve the tribological and mechanical properties. Specifically, this system is used because it can deposit not only a hard coating but also form a nitrogen diffusion layer that can enhance the load-bearing capacity of the sample and coating adhesion with the substrate. The XRD shows that vanadium nitride (VN) coating is polycrystalline, with a favored orientation along the (200) plane. The SEM results depict that at 673 K, the surface consists of uniformly disseminated spherical nanoparticles agglomerate to form coralloid granular nitrides. At 723 K, polygonal particles are uniformly distributed over the entire surface. The thickness of vanadium nitride films is 0.6 and 1.1 μm for 673 K and 723 K temperatures. The hardness of the sample increased up to 3 times over the untreated sample, whereas mechanical properties, including elastic modulus, and hardness-elastic modulus ratios H/E,H2/E,H3/E2 are upgraded, specifically at 723 K. Remarkably, the wear rates are reduced more than ten times, and a significant decrease in friction coefficient due to the deposition of VN coating. After the ball-on-disc wear analysis, the wear track is smooth and narrow for coated samples and still covered with vanadium and nitrogen elements, which indicates deposited coating is not detached from the substrate. It shows that VN coating can be deposited effectively to enhance the mechanical and tribological properties of AISI-420 steel.

In this study, a combination of conventional plasma nitriding and cathodic cage plasma deposition (CCPD) at different temperatures (400 and 450 °C) is implemented to enhance the surface properties of AISI-M2 steel. This combination effectively improves the surface hardness and the formation of a favorable hardness gradient toward the core, which would benefit the load-bearing capacity of substrate. The duplex-treated samples exhibit iron nitrides Fe4N, Fe2−3N and titanium nitride TiN phases. The thickness of the hard-TiN layer is 1.35 and 2.37 μm, whereas the combined thickness of the hard film and diffusion layer is 87 and 124 μm, for treatment at 400 and 450 °C, respectively. The wear rate and friction coefficient are dramatically reduced by duplex treatment. The oxidative wear mechanism and adhesive wear mechanism are dominant for duplex-treated samples. This study suggests that the cathodic cage plasma deposition technique can attain a combination of hard film and diffusion layer. The plasma nitriding before CCPD is beneficial for attaining an adequate nitrogen diffusion layer thickness. The drawbacks of conventional TiN film deposition, such as “egg-shell” problems, can be removed.

Cutting tools made of high-speed steel have significant economic and technological importance. To enhance their productivity, thermochemical treatments are sought to improve both surface mechanical and tribological properties. Plasma nitriding and thin film deposition are widely employed for this purpose. In this study, modifications were made to M2 high-speed steel drills through plasma nitriding at temperatures of 400°C and 450°C. Cathodic cage TiN plasma deposition was also performed, varying the dwell time at a fixed temperature of 450°C. Characterization techniques included optical microscopy, X-ray diffraction (XRD), Vickers microhardness testing, and scanning electron microscopy (SEM). Performance tests were carried out to evaluate the behavior of the drills in relation to wear when machining AISI 1020 steel. It was observed that longer deposition times promote more uniform and thicker layers, and higher nitriding temperatures result in thicker nitride layers. An increase in hardness was noticeable in all deposition and nitriding treatments, with the nitrided samples exhibiting the highest hardness. During performance tests, the cathodic cage plasma TiN deposition demonstrated greater potential for application in HSS drills, with a treatment lasting 4 h providing the best results.

This study investigated the wear resistance of AA1050 aluminum alloy coated using plasma deposition with a vanadium cathode cage and evaluated the effect of subsequently applying a plasma nitriding process to the coated sample. The treatments were carried out at 400°C for 3 hours. To evaluate the composition, thickness and wear resistance of the layers formed, X-ray fluorescence (XRF), scanning electron microscopy (SEM) and fixed ball micro-abrasive wear tests were applied. The treatments altered the wear mechanisms, with the treated samples also showing the two- and three-body wear modes, compared to the aluminium alloy, which only showed the two-body wear mode. The sample coated using only the cathodic cage deposition technique obtained a greater layer thickness (7.6 μm) and better wear resistance, with a reduction of around 83% in the worn volume compared to the 1050 aluminum alloy. However, the subsequent plasma nitriding process proved to be detrimental to the tribological properties of the coating formed, reducing the layer thickness (3.2 μm) and decreasing wear resistance.

AISI-420 martensitic steel is used in several applications due to its high corrosion resistance. A niobium nitride coating is deposited on steel by cathodic cage plasma deposition (CCPD) to upgrade the surface properties. The X-ray diffraction shows that the coating has a tetragonal Nb4N5 structure in each condition. The nano-hardness of the untreated sample (2.5 GPa) is increased up to 15.5 and 18.7 GPa at 400°C and 450°C, respectively. A ball-on-disc wear tester is applied for wear analysis, and the wear rate is found to be reduced up to six times by coating. This study shows that the CCPD can be used successfully for depositing niobium nitride coating with outstanding mechanical and tribological properties of AISI-420 steel.

AISI-1045 steel is a medium-carbon, medium-strength steel that usually requires surface engineering to be usable in industrial applications. Using the cathodic cage plasma deposition technique, transition metal (Nb, V, W) nitride coating is deposited on this steel using cathodic cage lids of these metals. The hardness of untreated steel (1.8 GPa) is upgraded to 11.2, 12.2, and 9.7 GPa for niobium nitride, vanadium nitride, and tungsten nitride coating, respectively. The elastic modulus, the ratio of hardness-elastic modulus (H/E, H2/E, and H3/E2), and the plasticity factor depict the improvement in mechanical and elastic properties. The sample treated with a niobium cage lid exhibits the Nb4N5 phase, the vanadium cage lid shows the VN phase (along with the Fe4N phase), and the tungsten cage lid consists of W2N3, WFeN2, and Fe4N phases. Among these coatings, the thickness of niobium nitride coating is maximum (1.87 μm), and a low deposition rate is obtained for tungsten nitride coating (0.83 μm). In addition to this coating, a nitrogen diffusion zone (∼60 μm) is also formed beneath the coating, which creates a hardness gradient between the coating and the substrate. The ball-on-disc wear tester shows that niobium nitride coating deposition reduces the wear rate from 19.5 × 10−3 to 8.8 × 10−3 mm3/N m and exhibits excellent wear performance.

Synthesis of molybdenum oxide on AISI-316 steel using cathodic cage plasma deposition at cathodic and floating potential

Zinc-oxide (ZnO), a solid lubricant coating, can increase the wear resistance of steels by working as a self-lubricant. In this study, ZnO film is synthesized using the cathodic cage plasma deposition (CCPD) technique, using galvanized steel cathodic cage (steel cage with zinc coating). The effect of gas composition (H2 is added in Ar-O2) is investigated to optimize the film properties. The surface hardness is increased more than twice in each processing condition. The deposited film shows ZnO phases for samples treated with low hydrogen contents and a combination of ZnO and magnetite phase (Fe3O4) with higher hydrogen contents. The thickness of film reduced from 1.28 μm to 0.5 μm by increasing the hydrogen composition. The wear resistance is expressively increased by film deposition, and the abrasive wear mechanism is changed to an adhesive wear mechanism. A significant decrease in wear rate is observed, specifically by increasing the hydrogen contents. The friction coefficient as a function of sliding distance is smoother and lower than the base material in each condition. This study suggests that the CCPD technique can effectively deposit the solid lubricant coating of ZnO, and it can be used to enhance the tribological properties of steel samples. Moreover, this technique is convenient due to its better deposition efficiency, eco-friendly (no chemicals are involved), simple and relatively low-cost equipment, and low processing temperature. Thus, it can be advantageous for industrial sectors interested in materials with exceptional tribological properties.

Improved wear resistance of AISI-4340 steel by Ti–Nb–C–N and MoS2 composite coating by cathodic cage plasma deposition

Surface modification of AISI 316 steel by α-MoO3 thin films grown using cathodic cage plasma deposition

Two cathodic arc plasma deposition processes have been used to deposit niobium nitride films in ambient nitrogen: (a) cathodic arc plasma deposition without dynamic mixing and (b) cathodic arc plasma deposition with energetic ion dynamic mixing. Smooth and continuous niobium nitride films were fabricated at low temperature in process (b) but at higher temperature (500 °C) in process (a). The effects of the substrate temperature on the film composition and preferred orientation were investigated. In process (a), films deposited at room temperature and 300 °C exhibited a preferred orientation of (220) whereas those deposited at 500 °C showed a preferred orientation of (200). The nitrogen content in the film synthesized in process (b) is higher than that in the films deposited in process (a). Our results show that with energetic ion dynamic mixing, niobium nitride films with excellent properties can be fabricated at low substrate temperature using a niobium metal arc plasma source in a nitrogen plasma immersion configuration.

Improved surface properties of AISI-420 steel by Ti[sbnd]C based coating using graphite cathodic cage with titanium lid in plasma deposition