Rosemary Jones, Giulio D’Acunto, Payam Shayesteh, Indiana Pinsard, F. Rochet, F. Bournel, J. Gallet, Ashley R Head, J. Schnadt
The introduction of atomic layer deposition (ALD), to the microelectronics industry has introduced a large number of new possible materials able to be deposited in layers with atomic thickness control. One such material is the high-κ oxide HfO2; thermally stable and ultrathin HfO2 films deposited by ALD are a significant contender to replace SiO2 as the gate oxide in capacitor applications. We present a mechanistic study of the first deposition cycle of HfO2 on the Si(111) surface using tetrakis(dimethylamido) hafnium (TDMAHf) and water as precursors using operando ambient pressure x-ray photoelectron spectroscopy. Here, we show that the hydroxylation of the clean Si(111) surface by residual water vapor, resulting in a 0.3 monolayer coverage of hydroxyls, leads to instantaneous full surface coverage of TDMAHf. The change in the atomic ratio of Hf to C/N found during the first deposition half-cycle, however, does not match the assumed immediate ligand loss through reaction with surface hydroxyls. One would expect an immediate loss of ligands, indicated by a Hf:N ratio of approximately 1:3 as TDMAHf deposits onto the surface; however, a Hf:N ratio of 1:3.6 is observed. The partial hydroxylation on the Si(111) surface leads to binding through the TDMAHf ligand N atoms resulting in both N and CH3 being found remaining on the surface post water half-cycle. Although there is evidence of ligand exchange reactions occurring at Si–OH sites, it also seems that N binding can occur on bare Si, highlighting the complexity of the substrate/precursor reaction even when hydroxyls are present. Moreover, the initial low coverage of Si–OH/Si–H appears to severely limit the amount of Hf deposited, which we hypothesize is due to the specific geometry of the initial arrangement of Si–OH/Si–H on the rest- and adatoms.
{"title":"Operando study of HfO2 atomic layer deposition on partially hydroxylated Si(111)","authors":"Rosemary Jones, Giulio D’Acunto, Payam Shayesteh, Indiana Pinsard, F. Rochet, F. Bournel, J. Gallet, Ashley R Head, J. Schnadt","doi":"10.1116/6.0003349","DOIUrl":"https://doi.org/10.1116/6.0003349","url":null,"abstract":"The introduction of atomic layer deposition (ALD), to the microelectronics industry has introduced a large number of new possible materials able to be deposited in layers with atomic thickness control. One such material is the high-κ oxide HfO2; thermally stable and ultrathin HfO2 films deposited by ALD are a significant contender to replace SiO2 as the gate oxide in capacitor applications. We present a mechanistic study of the first deposition cycle of HfO2 on the Si(111) surface using tetrakis(dimethylamido) hafnium (TDMAHf) and water as precursors using operando ambient pressure x-ray photoelectron spectroscopy. Here, we show that the hydroxylation of the clean Si(111) surface by residual water vapor, resulting in a 0.3 monolayer coverage of hydroxyls, leads to instantaneous full surface coverage of TDMAHf. The change in the atomic ratio of Hf to C/N found during the first deposition half-cycle, however, does not match the assumed immediate ligand loss through reaction with surface hydroxyls. One would expect an immediate loss of ligands, indicated by a Hf:N ratio of approximately 1:3 as TDMAHf deposits onto the surface; however, a Hf:N ratio of 1:3.6 is observed. The partial hydroxylation on the Si(111) surface leads to binding through the TDMAHf ligand N atoms resulting in both N and CH3 being found remaining on the surface post water half-cycle. Although there is evidence of ligand exchange reactions occurring at Si–OH sites, it also seems that N binding can occur on bare Si, highlighting the complexity of the substrate/precursor reaction even when hydroxyls are present. Moreover, the initial low coverage of Si–OH/Si–H appears to severely limit the amount of Hf deposited, which we hypothesize is due to the specific geometry of the initial arrangement of Si–OH/Si–H on the rest- and adatoms.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"46 17-18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140418995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Epoxy coatings are widely used on metal surfaces in marine environments, but are subject to corrosion. How to improve the corrosion resistance of such materials has therefore become an important research topic. In this study, the corrosion inhibitor 2-mercaptobenzimidazole (MBI) was added to the organic coating of the epoxy resin on the surface of the copper-62 alloy to extend the service life of the coating in marine environments. The corrosion inhibition efficiency of MBI for the copper-62 alloy in simulated marine environments was investigated by means of immersion corrosion tests, Tafel polarization tests, and electrochemical impedance spectroscopy (EIS). The effects of MBI on the damage process and water transport of epoxy coatings were also studied by EIS. It has been shown that MBI acts as an adsorption corrosion inhibitor by electro-attractively adsorbing on the surface of a copper substrate. For a total mass fraction of 0.5 wt. %, the corrosion inhibition efficiency was more than 90%, and the corrosion current density of the copper-62 alloy in simulated seawater with MBI was 6.01 × 10−7 A cm−2. The corrosion current density of the copper-62 alloy in simulated seawater is 1.382 × 10−5 A cm−2. When MBI was added to the epoxy organic coating at a ratio of 0.5 wt. %, the diffusion coefficient of the coating was as low as 9.72 × 10−11 cm2 s−1, and the time to failure of the coating was extended to 1656h, compared to the epoxy coating without the corrosion inhibitor. It has been demonstrated that the addition of MBI can increase the service life of copper-62 alloy/epoxy coatings in marine environments effectively.
环氧树脂涂料广泛应用于海洋环境中的金属表面，但容易受到腐蚀。因此，如何提高此类材料的耐腐蚀性已成为一个重要的研究课题。本研究在铜-62 合金表面的环氧树脂有机涂层中添加了缓蚀剂 2-巯基苯并咪唑（MBI），以延长涂层在海洋环境中的使用寿命。通过浸泡腐蚀试验、塔菲尔极化试验和电化学阻抗谱（EIS），研究了 MBI 在模拟海洋环境中对铜-62 合金的缓蚀效果。EIS 还研究了 MBI 对环氧涂层的破坏过程和水迁移的影响。研究表明，MBI 通过电吸引吸附在铜基材表面，起到吸附缓蚀剂的作用。在总质量分数为 0.5 wt. % 时，缓蚀效率超过 90%，铜-62 合金在含 MBI 的模拟海水中的腐蚀电流密度为 6.01 × 10-7 A cm-2。铜-62 合金在模拟海水中的腐蚀电流密度为 1.382 × 10-5 A cm-2。当 MBI 以 0.5 wt. % 的比例添加到环氧有机涂层中时，涂层的扩散系数低至 9.72 × 10-11 cm2 s-1，与未添加缓蚀剂的环氧涂层相比，涂层的失效时间延长至 1656h。实验证明，添加 MBI 可有效提高铜-62 合金/环氧涂层在海洋环境中的使用寿命。
{"title":"2-mercaptobenzimidazole inhibits corrosion and prolongs the lifetime of an epoxy resin coating on a copper-62 alloy surface in a simulated marine environment at 40 °C","authors":"Jingkang Chen, Xu Li, Xujie Xiao, Chengfei Zhu","doi":"10.1116/6.0003203","DOIUrl":"https://doi.org/10.1116/6.0003203","url":null,"abstract":"Epoxy coatings are widely used on metal surfaces in marine environments, but are subject to corrosion. How to improve the corrosion resistance of such materials has therefore become an important research topic. In this study, the corrosion inhibitor 2-mercaptobenzimidazole (MBI) was added to the organic coating of the epoxy resin on the surface of the copper-62 alloy to extend the service life of the coating in marine environments. The corrosion inhibition efficiency of MBI for the copper-62 alloy in simulated marine environments was investigated by means of immersion corrosion tests, Tafel polarization tests, and electrochemical impedance spectroscopy (EIS). The effects of MBI on the damage process and water transport of epoxy coatings were also studied by EIS. It has been shown that MBI acts as an adsorption corrosion inhibitor by electro-attractively adsorbing on the surface of a copper substrate. For a total mass fraction of 0.5 wt. %, the corrosion inhibition efficiency was more than 90%, and the corrosion current density of the copper-62 alloy in simulated seawater with MBI was 6.01 × 10−7 A cm−2. The corrosion current density of the copper-62 alloy in simulated seawater is 1.382 × 10−5 A cm−2. When MBI was added to the epoxy organic coating at a ratio of 0.5 wt. %, the diffusion coefficient of the coating was as low as 9.72 × 10−11 cm2 s−1, and the time to failure of the coating was extended to 1656h, compared to the epoxy coating without the corrosion inhibitor. It has been demonstrated that the addition of MBI can increase the service life of copper-62 alloy/epoxy coatings in marine environments effectively.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"22 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140420324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a Cu–Mo alloying layer with improved properties was fabricated by high current pulsed electron beam (HCPEB) irradiation. The microstructure of the modified layer was investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness and friction properties were also measured. After HCPEB irradiation, nano Mo particles, solid solution, and long-period superlattice structures were generated on the surface of Cu–Mo alloys, together with the formation of defect structures. These microstructures led to a significant increase in the surface hardness. The results of sliding wear tests indicated that the HCPEB-irradiated samples exhibited better properties compared with the initial one, which was attributed to the ultrafine Mo particles and the hardened surface.
本文利用大电流脉冲电子束（HCPEB）辐照技术制备了具有更好性能的铜钼合金层。通过 X 射线衍射、扫描电子显微镜和透射电子显微镜研究了改性层的微观结构。同时还测量了微硬度和摩擦性能。经 HCPEB 辐照后，铜钼合金表面产生了纳米钼颗粒、固溶体和长周期超晶格结构，并形成了缺陷结构。这些微结构显著提高了表面硬度。滑动磨损测试结果表明，与初始样品相比，经过 HCPEB 辐照的样品具有更好的性能，这归功于超细 Mo 粒子和硬化的表面。
{"title":"Microstructures and improved properties of Cu–Mo alloys induced by high current pulsed electron beam irradiation","authors":"Fangqiang Guo, Conglin Zhang, Jintong Guan, Chengjian Ma, Zirun Yang, Qingfeng Guan","doi":"10.1116/6.0003374","DOIUrl":"https://doi.org/10.1116/6.0003374","url":null,"abstract":"In this paper, a Cu–Mo alloying layer with improved properties was fabricated by high current pulsed electron beam (HCPEB) irradiation. The microstructure of the modified layer was investigated by x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness and friction properties were also measured. After HCPEB irradiation, nano Mo particles, solid solution, and long-period superlattice structures were generated on the surface of Cu–Mo alloys, together with the formation of defect structures. These microstructures led to a significant increase in the surface hardness. The results of sliding wear tests indicated that the HCPEB-irradiated samples exhibited better properties compared with the initial one, which was attributed to the ultrafine Mo particles and the hardened surface.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"302 1‐2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140417942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Goldbeck, V. Piroli, J. S. Weber, C. D. Boeira, B. L. Perotti, N. K. Fukumasu, Fernando Alvarez, C. A. Figueroa, A. F. Michels
Hydrogenated amorphous carbon (a-C:H) is a type of coating vastly applied on steel alloys due to its low friction coefficient, high hardness, and chemical inertness. Also, its characteristic brilliant black color like onyx stone is desirable for decorative applications. Despite the beneficial properties conferred to ferrous substrates, the adhesion of a-C:H films is weakened by its residual stress. In order to improve the adhesion of a-C:H films/steel alloy structures, one adopted strategy is the addition of an interlayer. This research investigated the influence of the bias voltage applied on the deposition of hydrogenated amorphous silicon carbide (a-SiCx:H) interlayers, with tetramethylsilane (TMS) as the precursor, to promote adhesion in a-C:H/a-SiCx:H/ferrous alloy structures for decorative applications. The thicker interlayer was achieved at −600 V. Two regimes were proposed to explain this behavior considering ionization rates and resputtering rates and chemical reactions in plasma. The chemical structure in different regions of the a-SiCx:H interlayer was analyzed in detail. An increase in the applied bias voltage leads to oxygen incorporation at the a-C:H/a-SiCx:H interface. Higher bias voltages result in lower silicon content at the a-SiCx:H/steel interface, which is correlated to the −800 V sample’s poor adhesion. Finally, we have included a discussion about a new range of loads when a decorative piece is held by the hand where the critical loads for delamination of a-C:H coatings measured here are good enough for decorative applications.
{"title":"Bias voltage influence on the a-SiCx:H interlayer deposition using tetramethylsilane: Decorative applications of a-C:H thin films on steel","authors":"M. Goldbeck, V. Piroli, J. S. Weber, C. D. Boeira, B. L. Perotti, N. K. Fukumasu, Fernando Alvarez, C. A. Figueroa, A. F. Michels","doi":"10.1116/6.0003328","DOIUrl":"https://doi.org/10.1116/6.0003328","url":null,"abstract":"Hydrogenated amorphous carbon (a-C:H) is a type of coating vastly applied on steel alloys due to its low friction coefficient, high hardness, and chemical inertness. Also, its characteristic brilliant black color like onyx stone is desirable for decorative applications. Despite the beneficial properties conferred to ferrous substrates, the adhesion of a-C:H films is weakened by its residual stress. In order to improve the adhesion of a-C:H films/steel alloy structures, one adopted strategy is the addition of an interlayer. This research investigated the influence of the bias voltage applied on the deposition of hydrogenated amorphous silicon carbide (a-SiCx:H) interlayers, with tetramethylsilane (TMS) as the precursor, to promote adhesion in a-C:H/a-SiCx:H/ferrous alloy structures for decorative applications. The thicker interlayer was achieved at −600 V. Two regimes were proposed to explain this behavior considering ionization rates and resputtering rates and chemical reactions in plasma. The chemical structure in different regions of the a-SiCx:H interlayer was analyzed in detail. An increase in the applied bias voltage leads to oxygen incorporation at the a-C:H/a-SiCx:H interface. Higher bias voltages result in lower silicon content at the a-SiCx:H/steel interface, which is correlated to the −800 V sample’s poor adhesion. Finally, we have included a discussion about a new range of loads when a decorative piece is held by the hand where the critical loads for delamination of a-C:H coatings measured here are good enough for decorative applications.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"22 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140420321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lifetime and biocompatibility of orthopedic implants are crucial in meeting the new challenges brought about by the fall in the patient age and the aging population. The high-load surfaces in contact with the biological environment must display enhanced tribological properties, biocompatibility, and reduced metal ion release in long-term clinical performance. Surface modification techniques such as nitriding can significantly improve the in-service behavior of the medical-grade alloys in current use. We report on a novel approach for nitriding of CoCrMo alloys using high power impulse magnetron sputtering (HIPIMS) discharge. The new nitriding process has been successfully carried out at the National HIPIMS Technology Centre at Sheffield Hallam University, UK, in an industrial size Hauzer 1000-4 system enabled with HIPIMS technology. While the nitriding ion flux is controlled by the HIPIMS magnetron plasma source, the ion energy can be independently set via the substrate bias. Implementing the HIPIMS source allows reducing the operational pressure by one order of magnitude compared to conventional dc plasma nitriding (DCPN). Plasma analyses have identified significantly enhanced production of ions of molecular nitrogen (N2+), atomic nitrogen (N+), and N2H+ radicals in the HIPIMS discharge compared to DCPN. Because of the low pressure of operation of the HIPIMS process, the energy of ions is similar to the bias voltage, whereas the high pressures used in DCPN cause severe losses in ion energy due to scattering collisions within the sheath. The high flux and high ion energy are primarily responsible for achieving a fourfold increase in process productivity as compared to state-of-the-art plasma nitriding processes. The nitrided surface layers exhibit excellent mechanical and tribological properties, which bring about significant improvements in hardness, fracture toughness, and wear. The protective function of the nitrided layer against corrosion in the aggressive environments of simulated body fluid is remarkably augmented. The barrier properties of the nitrided layer have been demonstrated through a reduction in metal ion release by as much as a factor of 2, 4, and 10 for Co, Cr, and Mo, respectively.
{"title":"Novel high-efficiency plasma nitriding process utilizing a high power impulse magnetron sputtering discharge","authors":"A. Ehiasarian, P. Hovsepian","doi":"10.1116/6.0003277","DOIUrl":"https://doi.org/10.1116/6.0003277","url":null,"abstract":"Lifetime and biocompatibility of orthopedic implants are crucial in meeting the new challenges brought about by the fall in the patient age and the aging population. The high-load surfaces in contact with the biological environment must display enhanced tribological properties, biocompatibility, and reduced metal ion release in long-term clinical performance. Surface modification techniques such as nitriding can significantly improve the in-service behavior of the medical-grade alloys in current use. We report on a novel approach for nitriding of CoCrMo alloys using high power impulse magnetron sputtering (HIPIMS) discharge. The new nitriding process has been successfully carried out at the National HIPIMS Technology Centre at Sheffield Hallam University, UK, in an industrial size Hauzer 1000-4 system enabled with HIPIMS technology. While the nitriding ion flux is controlled by the HIPIMS magnetron plasma source, the ion energy can be independently set via the substrate bias. Implementing the HIPIMS source allows reducing the operational pressure by one order of magnitude compared to conventional dc plasma nitriding (DCPN). Plasma analyses have identified significantly enhanced production of ions of molecular nitrogen (N2+), atomic nitrogen (N+), and N2H+ radicals in the HIPIMS discharge compared to DCPN. Because of the low pressure of operation of the HIPIMS process, the energy of ions is similar to the bias voltage, whereas the high pressures used in DCPN cause severe losses in ion energy due to scattering collisions within the sheath. The high flux and high ion energy are primarily responsible for achieving a fourfold increase in process productivity as compared to state-of-the-art plasma nitriding processes. The nitrided surface layers exhibit excellent mechanical and tribological properties, which bring about significant improvements in hardness, fracture toughness, and wear. The protective function of the nitrided layer against corrosion in the aggressive environments of simulated body fluid is remarkably augmented. The barrier properties of the nitrided layer have been demonstrated through a reduction in metal ion release by as much as a factor of 2, 4, and 10 for Co, Cr, and Mo, respectively.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"47 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140421915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Am N4,5 (4d3/2 and 4d5/2) and Am O4,5 (5d3/2 and 5d5/2) x-ray absorption spectroscopy (XAS) of americium sesquioxide (Am2O3) and americium dioxide (AmO2) has been evaluated with FEFF, a Green's function–based, multiple scattering code. Taking guidance from the intermediate coupling model (ICM), applicable to local and nonmagnetized samples, it is possible to completely reconstruct the experimental results for the N4,5 spectra, including the observed differences between the Am2O3 and the AmO2 cases. Although complicated by a more asymmetric line shape and difficult background variations, the FEFF analysis confirms the absence of core hole angular momentum coupling in Am O4,5 spectroscopy.
使用基于格林函数的多重散射代码 FEFF 对倍二氧化镅（Am2O3）和二氧化镅（AmO2）的 Am N4,5 （4d3/2 和 4d5/2）和 Am O4,5 （5d3/2 和 5d5/2）X 射线吸收光谱（XAS）进行了评估。在适用于局部和非磁化样品的中间耦合模型（ICM）的指导下，可以完全重建 N4,5 光谱的实验结果，包括观察到的 Am2O3 和 AmO2 之间的差异。尽管由于线形不对称和背景变化复杂，FEFF 分析证实 Am O4,5 光谱中不存在核洞角动量耦合。
{"title":"FEFF analysis of americium oxides","authors":"J. G. Tobin, S.-W. Yu, D. Shuh, S. Butorin","doi":"10.1116/6.0003428","DOIUrl":"https://doi.org/10.1116/6.0003428","url":null,"abstract":"The Am N4,5 (4d3/2 and 4d5/2) and Am O4,5 (5d3/2 and 5d5/2) x-ray absorption spectroscopy (XAS) of americium sesquioxide (Am2O3) and americium dioxide (AmO2) has been evaluated with FEFF, a Green's function–based, multiple scattering code. Taking guidance from the intermediate coupling model (ICM), applicable to local and nonmagnetized samples, it is possible to completely reconstruct the experimental results for the N4,5 spectra, including the observed differences between the Am2O3 and the AmO2 cases. Although complicated by a more asymmetric line shape and difficult background variations, the FEFF analysis confirms the absence of core hole angular momentum coupling in Am O4,5 spectroscopy.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"88 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140423884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. P. Moffat, S. Sharp, J. Provines, S. R. Agnew, J. M. Fitz-Gerald
The application of protective organic coatings is one of the most effective and commonly used corrosion mitigation strategies. To maintain the protective nature of coatings on long-term-exposed surfaces such as steel bridge components, coatings must be periodically removed and reapplied. A relatively new method called laser ablation coating removal (LACR), which incorporates a high energy nanosecond pulsed laser beam in combination with a high efficiency filtration system, allows for safe and effective removal of coatings and contamination from metal surfaces. In this study, LACR cleaning is tested on legacy bridge steel components to investigate the effect on substrate cleanliness and steel mechanical properties. These bridge sections were never blasted and contain a 20–100 μm thick mill-scale layer (iron oxide) below several coating layers (including lead-rich coatings). The top micron of the oxide layer is melted by LACR and also thermally insulates the underlying steel and prevents any melting within the metallic substrate. The resulting surfaces are analyzed using microscopy, hardness testing, tensile, and fatigue testing, and it is shown that LACR does not cause any measurable detrimental effects to the bulk mechanical properties of the bridge steel, as well as effectively removes all paint coatings. Furthermore, adhesion testing on LACR-cleaned substrates shows excellent adhesion, qualifying above adhesion requirements for coated steel.
{"title":"Assessing the feasibility of laser ablation coating removal (LACR) on legacy bridge steel: Coating removal and adhesion, and effects on mechanical properties","authors":"W. P. Moffat, S. Sharp, J. Provines, S. R. Agnew, J. M. Fitz-Gerald","doi":"10.1116/6.0003290","DOIUrl":"https://doi.org/10.1116/6.0003290","url":null,"abstract":"The application of protective organic coatings is one of the most effective and commonly used corrosion mitigation strategies. To maintain the protective nature of coatings on long-term-exposed surfaces such as steel bridge components, coatings must be periodically removed and reapplied. A relatively new method called laser ablation coating removal (LACR), which incorporates a high energy nanosecond pulsed laser beam in combination with a high efficiency filtration system, allows for safe and effective removal of coatings and contamination from metal surfaces. In this study, LACR cleaning is tested on legacy bridge steel components to investigate the effect on substrate cleanliness and steel mechanical properties. These bridge sections were never blasted and contain a 20–100 μm thick mill-scale layer (iron oxide) below several coating layers (including lead-rich coatings). The top micron of the oxide layer is melted by LACR and also thermally insulates the underlying steel and prevents any melting within the metallic substrate. The resulting surfaces are analyzed using microscopy, hardness testing, tensile, and fatigue testing, and it is shown that LACR does not cause any measurable detrimental effects to the bulk mechanical properties of the bridge steel, as well as effectively removes all paint coatings. Furthermore, adhesion testing on LACR-cleaned substrates shows excellent adhesion, qualifying above adhesion requirements for coated steel.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"286 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140417992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu-jie Zhou, Yang Li, Na Tan, Bing-wen Lu, Wei Yin, Guo-liang Zhang, Meng Liu, Yu-Jun Cai, Qi-yao Deng, Xu Kong
Improving the current-carrying friction and wear resistance of copper alloy current-carrying friction subsets effectively is a hot topic. In this paper, a method of preparing high melting point molybdenum-based coating on copper alloy surfaces by laser cladding technology is presented. A large current (106 A/m2) comparison experiment is carried out with a self-made current-carrying friction device, and the failure mechanism is analyzed. The results show that the molybdenum-based coating significantly improves the adhesion problem between the friction partner and the copper alloy substrate, while the thickness of the stress layer caused by the current-carrying friction is reduced by about 7 times. The molybdenum-based coating significantly reduces the surface arc rate and has a lower friction interface temperature, thus retaining the Al2O3 self-lubricating phase. The research in this paper is expected to provide extended research ideas for the surface protection of current-carrying friction subsets of copper alloys.
{"title":"Current-carrying tribological behavior of copper alloy matrix and molybdenum alloy coating at high current density","authors":"Yu-jie Zhou, Yang Li, Na Tan, Bing-wen Lu, Wei Yin, Guo-liang Zhang, Meng Liu, Yu-Jun Cai, Qi-yao Deng, Xu Kong","doi":"10.1116/6.0003313","DOIUrl":"https://doi.org/10.1116/6.0003313","url":null,"abstract":"Improving the current-carrying friction and wear resistance of copper alloy current-carrying friction subsets effectively is a hot topic. In this paper, a method of preparing high melting point molybdenum-based coating on copper alloy surfaces by laser cladding technology is presented. A large current (106 A/m2) comparison experiment is carried out with a self-made current-carrying friction device, and the failure mechanism is analyzed. The results show that the molybdenum-based coating significantly improves the adhesion problem between the friction partner and the copper alloy substrate, while the thickness of the stress layer caused by the current-carrying friction is reduced by about 7 times. The molybdenum-based coating significantly reduces the surface arc rate and has a lower friction interface temperature, thus retaining the Al2O3 self-lubricating phase. The research in this paper is expected to provide extended research ideas for the surface protection of current-carrying friction subsets of copper alloys.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"136 35","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140423300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Gogova, D. Tran, V. Stanishev, V. Jokubavicius, L. Vines, M. Schubert, R. Yakimova, P. P. Paskov, V. Darakchieva
A new growth approach, based on the hot-wall metalorganic chemical vapor deposition concept, is developed for high-quality homoepitaxial growth of Si-doped single-crystalline β-Ga2O3 layers on (010)-oriented native substrates. Substrate annealing in argon atmosphere for 1 min at temperatures below 600 °C is proposed for the formation of epi-ready surfaces as a cost-effective alternative to the traditionally employed annealing process in oxygen-containing atmosphere with a time duration of 1 h at about 1000 °C. It is shown that the on-axis rocking curve widths exhibit anisotropic dependence on the azimuth angle with minima for in-plane direction parallel to the [001] and maximum for the [100] for both substrate and layer. The homoepitaxial layers are demonstrated to have excellent structural properties with a β-Ga2O3(020) rocking curve full-widths at half-maximum as low as 11 arc sec, which is lower than the corresponding one for the substrates (19 arc sec), even for highly Si-doped (low 1019 cm−3 range) layers. Furthermore, the structural anisotropy in the layer is substantially reduced with respect to the substrate. Very smooth surface morphology of the epilayers with a root mean square roughness value of 0.6 nm over a 5 × 5 μm2 area is achieved along with a high electron mobility of 69 cm2 V−1 s−1 at a free carrier concentration n=1.9×1019 cm−3. These values compare well with state-of-the-art parameters reported in the literature for β-Ga2O3(010) homoepitaxial layers with respective Si doping levels. Thermal conductivity of 17.4 Wm−1K−1 is determined along the [010] direction for the homoepitaxial layers at 300 K, which approaches the respective value of bulk crystal (20.6 Wm−1K−1). This result is explained by a weak boundary effect and a low dislocation density in the homoepitaxial layers.
{"title":"High crystalline quality homoepitaxial Si-doped β-Ga2O3(010) layers with reduced structural anisotropy grown by hot-wall MOCVD","authors":"D. Gogova, D. Tran, V. Stanishev, V. Jokubavicius, L. Vines, M. Schubert, R. Yakimova, P. P. Paskov, V. Darakchieva","doi":"10.1116/6.0003424","DOIUrl":"https://doi.org/10.1116/6.0003424","url":null,"abstract":"A new growth approach, based on the hot-wall metalorganic chemical vapor deposition concept, is developed for high-quality homoepitaxial growth of Si-doped single-crystalline β-Ga2O3 layers on (010)-oriented native substrates. Substrate annealing in argon atmosphere for 1 min at temperatures below 600 °C is proposed for the formation of epi-ready surfaces as a cost-effective alternative to the traditionally employed annealing process in oxygen-containing atmosphere with a time duration of 1 h at about 1000 °C. It is shown that the on-axis rocking curve widths exhibit anisotropic dependence on the azimuth angle with minima for in-plane direction parallel to the [001] and maximum for the [100] for both substrate and layer. The homoepitaxial layers are demonstrated to have excellent structural properties with a β-Ga2O3(020) rocking curve full-widths at half-maximum as low as 11 arc sec, which is lower than the corresponding one for the substrates (19 arc sec), even for highly Si-doped (low 1019 cm−3 range) layers. Furthermore, the structural anisotropy in the layer is substantially reduced with respect to the substrate. Very smooth surface morphology of the epilayers with a root mean square roughness value of 0.6 nm over a 5 × 5 μm2 area is achieved along with a high electron mobility of 69 cm2 V−1 s−1 at a free carrier concentration n=1.9×1019 cm−3. These values compare well with state-of-the-art parameters reported in the literature for β-Ga2O3(010) homoepitaxial layers with respective Si doping levels. Thermal conductivity of 17.4 Wm−1K−1 is determined along the [010] direction for the homoepitaxial layers at 300 K, which approaches the respective value of bulk crystal (20.6 Wm−1K−1). This result is explained by a weak boundary effect and a low dislocation density in the homoepitaxial layers.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"9 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140424944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Annam, Swapneel Danayat, Avinash Nayal, Fatema Tarannum, Matthew Chrysler, Joseph H. Ngai, Jiechao Jiang, Aaron J. Schmidt, J. Garg
Perovskite materials, of which strontium titanate (STO) and its thin films are an example, have attracted significant scientific interest because of their desirable properties and the potential to tune thermal conductivity by employing several techniques. Notably, strontium titanate thin films on silicon (Si) substrates serve as a fundamental platform for integrating various oxides onto Si substrates, making it crucial to understand the thermal properties of STO on Si. This work investigates the thermal conductivity of STO thin films on an Si substrate for varying film thicknesses (12, 50, 80, and 200 nm) at room temperature (∼300 K). The thin films are deposited using molecular beam epitaxy on the Si substrate and their thermal conductivity is characterized using the frequency domain thermoreflectance (FDTR) method. The measured values range from 7.4 ± 0.74 for the 200 nm thick film to 0.8 ± 0.1 W m−1 K−1 for the 12 nm thick film, showing a large effect of the film thickness on the thermal conductivity values. The trend of the values is diminishing with the corresponding decrease in the thin film thickness, with a reduction of 38%–93% in the thermal conductivity values, for film thicknesses ranging from 200 to 12 nm. This reduction in the values is relative to the bulk single crystal values of STO, which may range from 11 to 13.5 W m−1 K−1 [Yu et al., Appl. Phys. Lett. 92, 191911 (2008) and Fumega et al., Phys. Rev. Mater. 4, 033606 (2020)], as measured by our FDTR-based experiment. The study also explores the evaluation of volumetric heat capacity (Cp). The measured volumetric heat capacity for the 200 nm thin film is 3.07 MJ m−3 K−1, which is in reasonable agreement with the values available in the literature.
透镜材料（钛酸锶（STO）及其薄膜就是其中的一个例子）因其理想的特性以及通过采用多种技术调节热导率的潜力而引起了科学界的极大兴趣。值得注意的是，硅（Si）基底上的钛酸锶薄膜是将各种氧化物集成到硅基底上的基本平台，因此了解硅基底上的 STO 的热特性至关重要。这项工作研究了硅基底上不同厚度（12、50、80 和 200 nm）的 STO 薄膜在室温（∼300 K）下的热导率。薄膜采用分子束外延技术沉积在硅基底上，其热导率采用频域热反射（FDTR）方法进行表征。测量值范围从 200 nm 厚薄膜的 7.4 ± 0.74 到 12 nm 厚薄膜的 0.8 ± 0.1 W m-1 K-1，表明薄膜厚度对热导率值有很大影响。随着薄膜厚度的相应减小，热导率值也呈减小趋势，薄膜厚度在 200 纳米到 12 纳米之间时，热导率值减小了 38% 到 93%。相对于 STO 的块状单晶而言，热导率值的降低幅度在 11 到 13.5 W m-1 K-1 之间 [Yu 等人，Appl.92, 191911 (2008) and Fumega et al.4, 033606 (2020)]，这是我们基于 FDTR 的实验所测得的结果。本研究还探讨了体积热容（Cp）的评估。测得的 200 纳米薄膜的体积热容为 3.07 MJ m-3 K-1，与文献中的数值基本一致。
{"title":"Thickness dependent thermal conductivity of strontium titanate thin films on silicon substrate","authors":"R. Annam, Swapneel Danayat, Avinash Nayal, Fatema Tarannum, Matthew Chrysler, Joseph H. Ngai, Jiechao Jiang, Aaron J. Schmidt, J. Garg","doi":"10.1116/6.0003320","DOIUrl":"https://doi.org/10.1116/6.0003320","url":null,"abstract":"Perovskite materials, of which strontium titanate (STO) and its thin films are an example, have attracted significant scientific interest because of their desirable properties and the potential to tune thermal conductivity by employing several techniques. Notably, strontium titanate thin films on silicon (Si) substrates serve as a fundamental platform for integrating various oxides onto Si substrates, making it crucial to understand the thermal properties of STO on Si. This work investigates the thermal conductivity of STO thin films on an Si substrate for varying film thicknesses (12, 50, 80, and 200 nm) at room temperature (∼300 K). The thin films are deposited using molecular beam epitaxy on the Si substrate and their thermal conductivity is characterized using the frequency domain thermoreflectance (FDTR) method. The measured values range from 7.4 ± 0.74 for the 200 nm thick film to 0.8 ± 0.1 W m−1 K−1 for the 12 nm thick film, showing a large effect of the film thickness on the thermal conductivity values. The trend of the values is diminishing with the corresponding decrease in the thin film thickness, with a reduction of 38%–93% in the thermal conductivity values, for film thicknesses ranging from 200 to 12 nm. This reduction in the values is relative to the bulk single crystal values of STO, which may range from 11 to 13.5 W m−1 K−1 [Yu et al., Appl. Phys. Lett. 92, 191911 (2008) and Fumega et al., Phys. Rev. Mater. 4, 033606 (2020)], as measured by our FDTR-based experiment. The study also explores the evaluation of volumetric heat capacity (Cp). The measured volumetric heat capacity for the 200 nm thin film is 3.07 MJ m−3 K−1, which is in reasonable agreement with the values available in the literature.","PeriodicalId":170900,"journal":{"name":"Journal of Vacuum Science & Technology A","volume":"39 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140427437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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