| 1. |
- Wu, Zhengtao, et al.
(författare)
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A comparative investigation on structure evolution of ZrN and CrN coatings against ion irradiation
- 2019
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Ingår i: Heliyon. - : ELSEVIER SCI LTD. - 2405-8440. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Binary ZrN and CrN nanostructured coatings deposited by magnetron sputtering were irradiated with 600 keV Kr3+ at room temperature. The ion irradiation fluences varied from 0 to 1 x 10(17) Kr3+/cm(-2). The results indicate the microstructure of the CrN illustrates higher stability during the Kr3+ ion irradiation compared to that of the ZrN. The ion irradiation produces surface etching of the CrN coating. However, the etching transfers to recrystallization and grain coarsening on the ZrN coating surface as the Kr3+ fluence increases.
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| 2. |
- Bakhit, Babak, 1983-, et al.
(författare)
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Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films
- 2021
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Ingår i: Scripta Materialia. - : Elsevier. - 1359-6462 .- 1872-8456. ; 191, s. 120-125
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Tidskriftsartikel (refereegranskat)abstract
- We recently showed that sputter-deposited Zr1-xTaxBy thin films have hexagonal AlB2-type columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. As-deposited layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we study the mechanical properties of ZrB2.4, Zr0.8Ta0.2B1.8, and Zr0.7Ta0.3B1.5 films annealed in Ar atmosphere as a function of annealing temperature Ta up to 1200 °C. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to Ta = 800 °C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5±1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at Ta > 800 °C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire Ta range.
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| 3. |
- Bakhit, Babak, 1983-, et al.
(författare)
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Multifunctional ZrB2-rich Zr1-xCrxBy thin films with enhanced mechanical, oxidation, and corrosion properties
- 2021
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 185
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Tidskriftsartikel (refereegranskat)abstract
- Refractory transition-metal (TM) diborides have high melting points, excellent hardness, and good chemical stability. However, these properties are not sufficient for applications involving extreme environments that require high mechanical strength as well as oxidation and corrosion resistance. Here, we study the effect of Cr addition on the properties of ZrB2-rich Zr1-xCrxBy thin films grown by hybrid high-power impulse and dc magnetron co-sputtering (Cr-HiPIMS/ZrB2-DCMS) with a 100-V Cr-metal-ion synchronized potential. Cr metal fraction, x = Cr/(Zr+Cr), is increased from 0.23 to 0.44 by decreasing the power Pzrb2 applied to the DCMS ZrB2 target from 4000 to 2000 W, while the average power, pulse width, and frequency applied to the HiPIMS Cr target are maintained constant. In addition, y decreases from 2.18 to 1.11 as a function of Pzrb2, as a result of supplying Cr to the growing film and preferential B resputtering caused by the pulsed Cr-ion flux. ZrB2.18, Zr0.77Cr0.23B1.52, Zr0.71Cr0.29B1.42, and Zr0.68Cr0.32B1.38 2 films have hexagonal AlB2 crystal structure with a columnar nanostructure, while Zr0.64Cr0.36B1.30 and Zr0.56Cr0.44B1.11 are amorphous. All films show hardness above 30 GPa. Zr0.56Cr0.44B1.11 alloys exhibit much better toughness, wear, oxidation, and corrosion resistance than ZrB2.18. This combination of properties makes Zr0.56Cr0.44B1.11 ideal candidates for numerous strategic applications.
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| 4. |
- Geng, Dongsen, et al.
(författare)
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An investigation on microstructure and milling performance of arc-evaporated TiSin/AlTiN film
- 2020
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Ingår i: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 709
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Tidskriftsartikel (refereegranskat)abstract
- In this work, TiSiN/AlTiN multilayer film was deposited on cemented-carbide solid end mill tools by cathodic arc evaporation. The multilayer consisted of CrN buffer layer, Al(0.6)7Ti(0.33)N adhesion layer, Ti0.9Si0.1N/Al(0.6)7Ti(0.33)N alternate layer, and Ti0.9Si0.1N outlayer. An investigation on microstructure, mechanical properties, high-temperature wear rate, and milling performance of TiSiN/AlTiN multilayer film was conducted. The results indicate that the as-deposited TiSiN/AlTiN film exhibits a mixture phase of fcc-TiN and fcc-(Ti, Al)N. The hardness and elastic modulus of the TiSiN/AlTiN film are 41.7 +/- 1.6 GPa and 340 +/- 17 GPa, respectively. The wear rate of TiSiN/AlTiN film changes slightly when the experiment temperature is below 400 degrees C, and then increases with the temperature increases to 600 degrees C. Indentation hardness of TiSiN/AlTiN changes can be maintained above 40 GPa upon annealing to 800 degrees C. However, the hardness of the film decreases from above 40 GPa to similar to 30.6 GPa when the annealing temperature increases to 1000 degrees C. During dry milling, the TiSiN/AlTiN film reduces the adhesion between the coated tool and machined material SKD 11, leading to a low cutting force and cutting temperature.
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| 5. |
- Geng, Dongsen, et al.
(författare)
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Impact of Si addition on oxidation resistance of Zr-Si-N nanocomposite films
- 2021
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Ingår i: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 183
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Tidskriftsartikel (refereegranskat)abstract
- Incorporating Si element into nitride films is known to enhance mechanical properties and oxidation resistance. Here, we reported the nanocomposite films of Zr-Si-N deposited using a hybrid deposited system combining rf magnetron sputtering from a Si3N4 target with dc magnetron sputtering from Zr target. Microstructure and oxidation resistance of Zr-Si-N nanocomposite films with 0-20.9 at.% Si content were investigated. The results indicated that the binary Zr-N film exhibits a typical columnar structure and the Zr-Si-N films become denser as the elevated Si content. The cross-section of film transforms to a dense and glassy structure when increasing the Si concentrations. The oxide scales of the Zr-Si-N films consist of ZrO2 nanograins and amorphous SiNx tissue. The introduction of the Si element significantly improves the oxidation resistance of the Zr-Si-N films due to the amorphous SiNx tissue phase suppresses both the inward diffusion of the oxygen and cracking in oxide scale caused by the phase transition from t-ZrO2 to m-ZrO2.
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| 6. |
- Li, Xu, et al.
(författare)
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Diamond-like/graphite-like carbon composite films deposited by high-power impulse magnetron sputtering
- 2020
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Ingår i: Diamond and related materials. - : ELSEVIER SCIENCE SA. - 0925-9635 .- 1879-0062. ; 106
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Tidskriftsartikel (refereegranskat)abstract
- Diamond-like carbon (DLC)/graphite-like carbon (GLC) composite films were prepared with high-power impulse magnetron sputtering (HiPIMS) using a mixture of Ar and Ne as the sputtering gas. The effect of the Ne fraction in the sputtering gas on the surface morphology, carbon bonding structure, microstructure, mechanical properties, residual stress, and tribological performance of the deposited films were characterized using laser scanning confocal microscopy, Raman spectroscopy, nano-indentation, residual stress tester, and friction and wear testing using a ball-on- plate tribometer, respectively. The films have a composite surface structure consisting of sp(2)-rich GLC microparticles embedded in an sp(3)-rich DLC matrix. Both components can be controlled to some degree by varying the Ne fraction. Specifically, as the Ne fraction is increased, both the number and size of the GLC microparticles decreases, while the sp(3) content increases. The GLC microparticles in the film can reduce the real contact area in friction testing, decreasing the friction coefficient, while the sp(3)-rich DLC phase enables the high hardness and wear resistance of the films. By adjusting the Ne fraction during the HiPIMS process, DLC/GLC composite films with low friction and high wear resistance can be generated.
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| 7. |
- Wu, Zhengtao, et al.
(författare)
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Cubic-structure Al-rich TiAlSiN thin films grown by hybrid high-power impulse magnetron co-sputtering with synchronized Al+ irradiation
- 2020
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Ingår i: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 385
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Tidskriftsartikel (refereegranskat)abstract
- Adding Si into transition-metal nitride hard coatings is known to enhance mechanical properties and oxidation resistance. At the same time, however, Si promotes precipitation of wurtzite-structure AlN in Ti1-xAlxN during deposition by magnetron sputtering or cathodic-arc-evaporation, resulting in a decrease in layer hardness. Here, we report nanocomposite films of metastable cubic NaCl-structure TiAlSiN deposited using a hybrid approach combining high-power impulse magnetron sputtering (HiPIMS) from an Al target with DC magnetron sputtering (DCMS) from TiSi targets (Al-HiPIMS/TiSi-DCMS) in which a substrate bias is synchronized to the metal-rich portion of each HiPIMS pulse. The Al/(Al + Ti) ratio is varied from 0.26 to 0.77 by adjusting the TiSi target power, while the Si content ranges from 7.6 to 10.3 at.%. Cubic-structure TiAlSiN solid solutions are obtained with a maximum Al/(Al + Ti) atomic ratio of 0.59 and 9.4 at.% Si. Excess Si segregates to grain boundaries to form a SiNx-rich tissue phase. The hardness H and elastic modulus E of cubic TiAlSiN films increase from H = 19.4 +/- 1.7 and E = 322 +/- 12 for TiAlSiN layer with Al/(Al + Ti) = 0.26 to H = 37.3 +/- 1.3 and E = 388 +/- 12 GPa for TiAlSiN layer with Al/(Al + Ti) = 0.59. The TiAlSiN films also exhibit a low intrinsic stress (-0.55 to 0.62 GPa), resulting in a combination of properties: superior hardness and low stress.
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| 8. |
- Wu, Zhengtao, et al.
(författare)
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Growth of dense, hard yet low-stress Ti0.40Al0.27W0.33N nanocomposite films with rotating substrate and no external substrate heating
- 2020
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : A V S AMER INST PHYSICS. - 0734-2101 .- 1520-8559. ; 38:2
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Tidskriftsartikel (refereegranskat)abstract
- W+ irradiation of TiAlN is used to demonstrate growth of dense, hard, and stress-free refractory nitride coatings with no external heating during reactive magnetron sputtering. Ti0.40Al0.27W0.33N nanocomposite films are deposited on Si(001) substrates using hybrid high-power impulse and dc magnetron cosputtering (HiPIMS and DCMS) in an industrial sputtering system employing substrate rotation during film growth from six cathodes. Two W targets powered by HiPIMS serve as a pulsed source of energetic W+ ions with incident fluxes analyzed by in situ time- and energy-resolved mass spectroscopy, while the remaining four targets (two elemental Ti targets and two Ti plates with Al plugs) are operated in the DCMS mode (W-HiPIMS/TiAl-DCMS) to provide a continuous flux of metal atoms and sustain a high deposition rate. A negative substrate bias V-s is applied only in synchronous with the W+-ion-rich portion of each HiPIMS pulse in order to provide film densification by heavy-ion irradiation of the TiAlN layers deposited between W+-ion exposures. W is selected for densification due to its high mass and relatively low reactivity with N-2, thus minimizing target poisoning while enhancing gas rarefaction. Dense Ti0.40Al0.27W0.33N alloy films, grown with no external substrate heating (substrate temperature T-s lower than 150 degrees C due to heat load from the plasma) and V-s=500V, exhibit a nanoindentation hardness of H=23.1GPa and an elastic modulus of E=378GPa, which are, respectively, 210% and 40% higher than for reference underdense DCMS Ti0.58Al0.42N films grown under the same conditions, but without W+ irradiation. The W ion bombardment does not affect the film stress state, which is compressive and low at 1.2GPa.
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| 9. |
- Wu, Zhengtao, et al.
(författare)
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Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr
- 2022
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Ingår i: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 436
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Tidskriftsartikel (refereegranskat)abstract
- Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr-interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to -60 V and -200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2-5 nm improves the resistance to oxidation at 500-600 ?& nbsp;as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 ?& nbsp;are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at -60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x < 2) and higher wear rates compared to multilayers grown at -60 V.
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| 10. |
- Wu, Zhengtao, et al.
(författare)
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In situ nanoindentation measurements of arc-evaporated Cr0.49Al0.51N, Al0.66Ti0.34N, and Al0.65Ti0.33Y0.02N films up to 800 degrees C
- 2020
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Ingår i: Journal of Vacuum Science and Technology B. - : A V S AMER INST PHYSICS. - 2166-2746 .- 2166-2754. ; 38:2
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the in situ hardness and elastic modulus measurements of arc-evaporated Cr0.49Al0.51N, Al0.66Ti0.34N, and Al0.65Ti0.33Y0.02N films are investigated using a high-temperature nanoindentation tester. It is found that the hardness of Cr0.49Al0.51N initially increases from 30.2 +/- 2.3GPa at room temperature (RT) and reaches a maximum of 33.2 +/- 2.4GPa at 600 degrees C before decreasing to 27.9 +/- 2.1GPa at 800 degrees C. However, the results for elastic modulus versus temperature follow a degraded trend, with 405 +/- 23GPa for RT, decreasing to 280 +/- 18GPa at 800 degrees C. Increases in the hardness and the elastic modulus can be achieved for both Al0.66Ti0.34N and Al0.65Ti0.33Y0.02N films as their temperatures increase. The addition of Y effectively promotes the hardness and the elastic modulus of Al0.66Ti0.34N at RT-300 degrees C. However, both hardness and elastic modulus change slightly as Y is incorporated at 300-800 degrees C.
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| 11. |
- Wu, Zhengtao, et al.
(författare)
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Investigation on plastic deformation of arc-evaporated AlCrSiN and AlCrSiON nanocomposite films by indentation
- 2022
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Ingår i: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 441
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Tidskriftsartikel (refereegranskat)abstract
- Nanoindentation produced plastic deformation of arc-evaporated AlCrSiN and AlCrSiON nanocomposite films deposited on cemented-carbide substrates was investigated. The nanoindentation tests have the maximum penetration depth of 250 nm. Microstructure evolution in the indents was indicated by focused-ion-beam cutting and transmission-electron-microscopy observation. The results indicate that both the AlCrSiN and the AlCrSiON nanocomposite films exhibit excellent plasticity without the occurrence of microcrack initiation and propagation in the indents and grain boundaries. The prominent pile-up phenomenon produced by plastic flow was observed in the indent of the AlCrSiON film. Incorporating O into the AlCrSiN reduces both hardness and toughness of the film. This produces the pile-up in the AlCrSiON film when exposed to a nanoindenter. Rotation of the (Cr, Al)N nanograins and deflection of self-organized multilayer interface contribute to the plastic deformation of the AlCrSiN. However, shear band, interface deflection, and grain rotation contribute to the nanoindentationinduced plastic deformation of the AlCrSiON film.
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| 12. |
- Wu, Zhengtao, et al.
(författare)
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Reprint of: Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr*
- 2022
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Ingår i: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 442
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Tidskriftsartikel (refereegranskat)abstract
- Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to -60 V and -200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2-5 nm improves the resistance to oxidation at 500-600 degrees C as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 degrees C are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at -60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x < 2) and higher wear rates compared to multilayers grown at -60 V.
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| 13. |
- Zhang, Quan, et al.
(författare)
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Improving the mechanical and anti-wear properties of AlTiN coatings by the hybrid arc and sputtering deposition
- 2019
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Ingår i: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 378
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Tidskriftsartikel (refereegranskat)abstract
- Arc-evaporated AITiN coatings with remarkable adhesion and thermal stability are widely used in manufacturing. However, the large residual stress and surface roughness limit their high-level applications for advanced machining. In this study, a hybrid technique combining cathodic arc evaporation and magnetron sputtering was utilized to enhance the mechanical properties and wear resistance of AlxTi1-xN with x = similar to 0.65. The hybrid AIM coatings exhibited a nano-multilayer architecture with alternating arc-evaporated and magnetron sputtered constituents, which decreased their residual stress from -7.1 GPa to about -5.0 GPa. In addition, the hybrid AlTiN showed higher indentation toughness than the monolithic coatings. The hybrid AITiN coating with a target sputtering power of 7.0 kW showed excellent wear resistance at room and high temperature. At 800 degrees C, the hybrid coatings mainly showed abrasive and oxidation wear, while the monolithic AITiN coating showed abrasive/oxidation wear and brittle failure.
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