11 research outputs found
Tribological and Mechanical Properties of the Nanostructured Superlattice Coatings with Respect to Surface Texture
Get PDFThis research is funded by the Latvian Council of Science, project āCarbon-rich self-healing multifunctional nanostructured smart coatings (NSC) for high-tech applications using high-power confined plasma technology for their depositionā, project No. 2019/1-0385.Ceramic Nanostructured Superlattice Coatings (NSC) have broad applicability to improve the partsā and assembliesā tribological and mechanical properties for the needs of the automotive and aerospace industries. Improving the material properties using nanocoatings for such a widely used material as, for example, bearing steel 100Cr6 makes it possible to improve the service life of machine parts. In this paper, the correlation dependence between tribological and mechanical properties of the NSC and its surface texture are considered to determine how much surface texture will affect the tribological performance of the coated workpieces, as well as the measuring and evaluation procedure of the nanocoatings, are presented. Three different NSC described by a general empirical formula {TiMe1Me2-CN/TiAlSi-N}n and based on the modified carbonitride/nitride non-stoichiometric chemical composition were created, and their tribological and mechanical properties measured and analyzed in the context with surface texture. NSC deposited by the advanced PVD (Physical vapor deposition) technique demonstrated significantly higher wear resistance (up to 28 times), reasonably lower friction coefficient (CoF) (up to 4 times), and significantly higher hardness of the coated workpieces (up to 7 times) versus substrate material. A strong correlation between the steady-state dry sliding friction, CoF, and the amplitude and functional surface texture parameters of tribo-track were observed. The first results of the initiated research regarding the correlation analysis of the tribological and mechanical properties, on the one hand, and surface texture, on the other hand, of the NSC are reported here. Ā© 2022 by the authors.Latvian Council of Science project No. 2019/1-0385; Institute of Solid-State Physics, University of Latvia has received funding from the European Union's Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2
Nanoindentation Response analysis of Thin Film Substrates-I: Strain Gradient-Divergence Approach
No full textNanoindentation is a widely-used method for sensitive exploration of the mechanical properties of micromechanical systems. We derive a simple empirical analysis technique to extract stress-strain field (SSF) gradient and divergence representations from nanoindentation data sets. Using this approach, local SSF gradients and structural heterogeneities can be discovered to obtain more detail about the sampleās microstructure, thus enhancing the analytic capacity of the nanoindentation technique. We demonstrate the application of the SSF gradient-divergence analysis approach to nanoindentation measurements of bulk silicon
Nanoindentation response analysis of thin film substrates-II: Strain hardening-softening oscillations in subsurface layer
No full textWe have extracted stress-strain field (SSF) gradient and divergence rep-resentations from nanoindentation data sets of bulk solids often used as thin film substrates: bearing and tooling steels, silicon, glasses, and fused silica. Oscillations of the stress-strain field gradient and divergence induced in the subsurface layer by the nanoindentation have been revealed. The oscillations are especially prominent in single indentation tests at shallow penetration depths, h<100 nm, whereas they are concealed in the averaged datasets of 10 and more single tests. The amplitude of the SSF divergence oscillations decays as a sublinear power-law when the indenter approaches deeper atomic layers, with an exponent -0.9 for the steel and -0.8 for the fused silica. The oscillations are interpreted as alternating strain hardening-softening plastic deformation cycles induced in the subsurface layer under the indenter load
TEMPERATÅŖRAS FLUKTUÄCIJU KORELATÄŖVÄ ANALÄŖZE CENTRALIZÄTÄS SILTUMAPGÄDES SISTÄMÄS
No full textÅ is raksts tika veltÄ«ts Tag&T1-korelogrammu fluktuÄciju pÄtÄ«jumiem, izmantojot asimetrisko temperatÅ«ras kontÅ«ru (TK) metodi, kas ļauj apkures sezonai (AS) atbilstoÅ”o (Tag'i; T1'i)-punktu kopas reprezentÄjoÅ”o AS-TK sadalÄ«t vairÄkos maza apjoma asimetriskos TK. Asimetriskie TK tika izmantoti, lai norobežotu nelielus (Tag'i; T1'i)-punktu apgabalus no pilnÄs Tag&T1-korelogrammas ar mÄrÄ·i izpÄtÄ«t temperatÅ«ras fluktuÄcijas apstÄkļos, kad regresora vai regresenta svÄrstÄ«bas TK bÄzes intervÄlÄ ir stipri ierobežotas. Asimetrisko TK izmantoÅ”ana temperatÅ«ras fluktuÄciju analÄ«zÄ Ä¼Äva izskaidrot jautÄjumu par regresenta, T1, fluktuÄcijÄm ar 33,40C lielu amplitÅ«du, T1ļ[49,6; 83,0], kamÄr Tagļ[-1; 0]. ArÄ« citviet pilnajÄ Tag&T1-korelogrammÄ bija novÄrojama salÄ«dzinoÅ”i liela turpgaitas temperatÅ«ras, T1, izkliede ar amplitÅ«du ">200C", kamÄr Ärgaisa temperatÅ«ra, Tag, mainÄ«jÄs 1-grÄda robežÄs: piem., kamÄr Tagļ[-3,5; -2,5], tikmÄr T1ļ[67,0; 88,6], vai citÄ gadÄ«jumÄ - kamÄr Tagļ[-6,5; -5,5], tikmÄr T1ļ[73,6; 95,1]. Turpgaitas temperatÅ«ras fluktuÄcijas atbilstoÅ”i gadÄ«juma lieluma normÄlajam sadalÄ«jumam Ä£enerÄ CSA statistiskÄ fona faktori, kamÄr Ärgaisa temperatÅ«ra ir "fiksÄta" TK bÄzes intervÄla robežÄs
Statistical Analysis of District Heating Processes Using Temperature Contour Approach
No full textThe article deals with correlation analysis of district heating (DH) processes using temperature contour (TC) approach based on investigation of the functional dependence between outdoor temperature, Tout, as the regressor, and DH process characterizing thermal or hydraulic parameters, PDH, as the regresent, e.g., supply and return water temperature, TS&TR, as well as water mass flow, V. The time series of outdoor temperature, {Tout'i}, and supply water temperature, {TS'i}, as well as Tout&TS-scatter plots of (Tout'i; TS'i)-point data set have been examined more in details. It has been shown that using TC-approach one can additively construct linear regression models corresponding separately to each TC, and thereafter combining these models together and creating full regression curve for whole Tout&TS-scatter plot. Also frequency distribution functions (FDF), dFr(Tout)&cFr(Tout) and dFr(TS)&cFr(TS), have been calculated for different size TC in order to explore corresponding (Tout'i; TS'i)-point data set immanent data structure. In the case of asymmetric TC it has been stated that (Tout'i; TS'i)-points most likely are uniformly distributed along TC base-interval. However, along TC contiguous-interval (Tout'i; TS'i)-points most likely are normally distributed
CentrÄlapkures procesu korelatÄ«vÄ analÄ«ze un to lineÄrie regresijas modeļi
No full textÅ Ä pÄtÄ«juma ietvaros tika detalizÄti iztirzÄta centralizÄtÄs siltumapgÄdes siltumnesÄja turpgaitas temperatÅ«ras, T1, kÄ regresenta korelatÄ«vÄ saistÄ«ba ar Ärgaisa temperatÅ«ru, Tag, kÄ regresoru, izmantojot korelatÄ«vÄs analÄ«zes rÄ«kus. Å ajÄ sakarÄ korelogrammas tika papildinÄtas ar konceptu par TagxT1 temperatÅ«ras lauku un tÄ strukturÄÅ”anu, pÄrklÄjot Tag&T1-korelogrammas ar temperatÅ«ras režģi, kuru veido 1x2-grÄdu TagxT1-Ŕūnu struktÅ«ra. Å ÄdÄ temperatÅ«ras režģī var uzskatÄmi izdalÄ«t specifiskus korelogrammas apgabalus, kurus pamatoti sauc par temperatÅ«ras kontÅ«riem (TK). Ar TK palÄ«dzÄ«bu no pilnÄs Tag&T1-korelogrammas, kura dotajÄ gadÄ«jumÄ sastÄvÄja no 4608 (Tag'i; T1'i)-punktiem, tika izdalÄ«ti atseviŔķi specifiski tÄs posmi un apgabali, kuri norobežoja no pilnÄs korelogrammas attiecÄ«gas (Tag'i; T1'i)-punktu apakÅ”kopas. Å Ä«s konkrÄtiem TK piederoÅ”Äs (Tag'i; T1'i)-punktu apakÅ”kopas tika detalizÄti izpÄtÄ«tas kÄ atseviŔķi statistiskie objekti. PadziļinÄtu un vairÄk detalizÄtu priekÅ”statu par Ŕīm ar TK saistÄ«tajÄm (Tag'i; T1'i)-punktu apakÅ”kopÄm kÄ statistiskajiem objektiem varÄja iegÅ«t, izskaitļojot to vidÄjos centrÄlo tendenÄu rÄdÄ«tÄjus un izkliedes rÄdÄ«tÄjus. Katram Å”Ädam TK tika aprÄÄ·inÄts korelÄcijas koeficients un tika izveidoti lineÄrie regresijas modeļi. Tag&T1-korelogrammas pÄtÄ«jumos vienmÄr aktuÄls ir bijis jautÄjums par iespÄjami atbilstÄ«gÄka regresijas modeļa konstruÄÅ”anu, kura piemÄrotÄ«ba tika novÄrtÄta ar determinÄcijas koeficienta, R^2, lielumu ā jo lielÄka R^2 vÄrtÄ«ba, jo augstÄka modeļa piemÄrotÄ«ba. DeterminÄcijas koeficients, R^2, procentuÄli parÄda, kÄdu (Tag'i; T1'i)-punktu izkliedes daļu kontrolÄ dotais regresijas vienÄdojums
SiltumenerÄ£Ätisko procesu analÄ«ze izmantojot pÄru korelÄcijas matricu metodi
No full textDarbÄ veikta centralizÄtÄs siltumapgÄdes (CSA) procesu padziļinÄta izpÄte, izmantojot korelatÄ«vÄs analÄ«zes metodes. Siltumtehnisko parametru korelatÄ«vÄs analÄ«zes svarÄ«ga sastÄvdaļa ir pÄru korelÄcijas matricu izskaitļoÅ”ana un korelogrammu izveidoÅ”ana, kas ļauj siltumtehnisko parametru korelatÄ«vo saistÄ«bu vizualizÄt un Ätri novÄrtÄt potenciÄlo regresijas modeļu funkcionÄlo formu. PÄtÄ«jumu gaitÄ tika noskaidrota CSA siltumtehnisko parametru korelatÄ«vÄ saistÄ«ba, izskaitļotas pÄru korelÄcijas matricas un sastÄdÄ«ta potenciÄlo regresoru-regresenta pÄru tabula ar mÄrÄ·i tÄlÄk attÄ«stÄ«t CSA regresijas modeļu izstrÄdÄÅ”anu. PÄru korelÄcijas matricas elementu vÄrtÄ«bas ir augstÄkÄ mÄrÄ atkarÄ«gas no izvÄlÄtÄs datu bÄzes apjoma un atbilstoÅ”Ä laika perioda. TÄpÄc pÄru korelÄcijas matricas var uzskatÄ«t par "jutÄ«gu" analÄ«zes instrumentu, ar kura palÄ«dzÄ«bu var noteikt potenciÄlos siltumtehnisko parametru pÄrus, kas izmantojami regresora-regresenta statusÄ
CentrÄlapkures procesu korelatÄ«vÄ analÄ«ze un to temperatÅ«ras spektroskopija
No full textÅ is raksts tika veltÄ«ts Tag&T1-korelogrammu pÄtÄ«jumiem, izmantojot temperatÅ«ras kontÅ«ru (TK) metodi, kas ļauj apkures sezonai (AS) atbilstoÅ”o (Tag'i; T1'i)-punktu kopu reprezentÄt kÄ AS-TK un sadalÄ«t to vairÄkos mazÄka apjoma sub-TKj. Å Ädi izveidotiem sub-TKj piederoÅ”Äs (Tag'i; T1'i)-punktu apakÅ”kopas tika detalizÄti izpÄtÄ«tas kÄ atseviŔķi statistiskie objekti. Vispirms tika izskaitļoti sub-TKj vidÄjie centrÄlo tendenÄu rÄdÄ«tÄji un (Tag'i; T1'i)-punktu izkliedes rÄdÄ«tÄji, lai iegÅ«tu padziļinÄtu priekÅ”statu par Ŕīm ar sub-TKj saistÄ«tajÄm (Tag'i; T1'i)-punktu apakÅ”kopÄm. TÄpat sub-TKj tika izmantoti, lai visu AS aptveroÅ”Äs pilnÄs Tag&T1-korelogrammas regresijas modeli izveidotu pÄc aditivitÄtes principa, apvienojot autonomo sub-TKj atbilstoÅ”os regresijas modeļus. VidÄjie (Tag'i; T1'i)-punktu izkliedes rÄdÄ«tÄji tika papildinÄti ar regresora un regresenta frekvenÄu sadalÄ«juma funkcijÄm. Å ajÄ sakarÄ tika izskaitļotas sub-TKj elementu diferenciÄlÄs un integrÄlÄs frekvenÄu sadalÄ«juma funkcijas (FSF), proti, dFSF(Tag)&dFSF(T1) un cFSF(Tag)& cFSF(T1), kas sadala attiecÄ«gi regresora, Tag, un regresenta, T1, vÄrtÄ«bas pa kategorizÄtiem klaÅ”u intervÄliem. PÄtÄ«jumÄ izmantoti 1- un 2-grÄdu gari klaÅ”u intervÄli, kuri nodroÅ”inÄja dFSF iegÅ«Å”anu ar vismaz 3%-augstu izŔķirtspÄju. TÄdÄjÄdi izskaitļotie Ärgaisa temperatÅ«ras, Tag, un siltumnesÄja turpgaitas temperatÅ«ras, T1, spektri dFSF(Tag)&dFSF(T1) nav neatkarÄ«gi temperatÅ«ras spektri, bet gan pa pÄriem korelatÄ«vi saistÄ«ti temperatÅ«ras spektri, proti, katram sub-TKj ir savs raksturÄ«gais Tagāspektrs un ar to asociÄtais T1āspektrs. No fizikÄ labi pazÄ«stamÄs fizikÄlo lielumu lÄ«dzÄ«bas teorijas aspekta Tagā un T1āspektrus varam aplÅ«kot kÄ katram sub-TKj raksturÄ«go regresora "ierosmes spektru" un ar to korelatÄ«vi saistÄ«to regresenta "atbildes spektru". NeatkarÄ«gi no sub-TKjļAS-TK izvÄles novÄrojama kopÄ«ga likumsakarÄ«ba: jo pie zemÄkÄm temperatÅ«rÄm novÄrojams regresora, Tag, "ierosmes spektrs", jo pie augstÄkÄm temperatÅ«rÄm atrodams regresenta, T1, "atbildes spektrs"
SiltumenerÄ£Ätisko procesu temperatÅ«ras spektroskopija un tiem atbilstoÅ”ie lineÄrie regresijas modeļi
No full textÅ is raksts tika veltÄ«ts Tag&T1-korelogrammu pÄtÄ«jumiem, izmantojot temperatÅ«ras kontÅ«ru (TK) metodi, kas ļauj apkures sezonai (AS) atbilstoÅ”o (Tag'i; T1'i)-punktu kopu reprezentÄt kÄ AS-TK un sadalÄ«t to vairÄkos mazÄka apjoma sub-TKj. TÄdÄjÄdi visu AS aptveroÅ”Äs pilnÄs Tag&T1-korelogrammu regresijas modeli var izveidot pÄc aditivitÄtes principa, apvienojot sub-TKj atbilstoÅ”os regresijas modeļus. DetalizÄtu un padziļinÄtu priekÅ”statu par TK piederoÅ”ajÄm (Tag'i; T1'i)-punktu apakÅ”kopÄm kÄ statistiskajiem objektiem var iegÅ«t, izskaitļojot to elementu diferenciÄlÄs un integrÄlÄs frekvenÄu sadalÄ«juma funkcijas (FSF), proti, dFSF(Tag)&dFSF(T1) un cFSF(Tag)& cFSF(T1), kas sadala attiecÄ«gi regresora, Tag, un regresenta, T1, vÄrtÄ«bas pa kategorizÄtu klaÅ”u intervÄliem. PÄtÄ«jumÄ izmantoti 1- un 2-grÄdu gari klaÅ”u intervÄli, kuri nodroÅ”inÄja dFSF iegÅ«Å”anu ar vismaz 3%-augstu izŔķirtspÄju. Tag&T1-korelogrammas pÄtÄ«jumos vienmÄr aktuÄls ir bijis jautÄjums par iespÄjami atbilstÄ«gÄka regresijas modeļa konstruÄÅ”anu, kura piemÄrotÄ«ba tika novÄrtÄta ar determinÄcijas koeficienta, R^2, lielumu ā jo lielÄka R^2 vÄrtÄ«ba, jo augstÄka modeļa piemÄrotÄ«ba
Tribological and Micromechanical Properties of the Nanostructured Carbonitride/Nitride Coatings of Transition Metals Alloyed by Hf and Nb
Get PDFThis research was funded by the Latvian Council of Science, project āCarbon-rich self-healing multifunctional nanostructured smart coatings (NSC) for high-tech applications using high-power confined plasma technology for their depositionā, project No. 2019/1-0385.In this article, the fabrication, characterization, tribological performance, and micromechanical properties of nanostructured smart coatings (NSC) based on the multilayered alternating carbonitride/nitride bilayer {TiMe-CN/TiAlSi-N}n system are discussed. The symbol āMeā denotes refractory metals Hf or Nb, and the index ānā shows the number of superlattice periods. The NSC samples were deposited onto bearing steel (100Cr6) substrates using a reactive high-power physical vapor deposition (PVD) technique that can be scaled up for industrial use. The deposited multilayered NSC contained crystalline nanometer-scale TiMe-CN/TiAlSi-N nanoparticles strengthened by Hf or Nb additives, which increased surface microhardness up to 3000 HV. The measured steady-state friction coefficient (CoF) was within the 0.2ā0.4 range, and a specific wear rate lower than 2 Ć 10ā6 mm3/Nm was observed in the dry friction regime. The impact of NSC substrate hardness and NSC coating thickness on microhardness measurement values was investigated. A thicker coating provided a higher integrated (coating + substrate) microhardness value at a lower indentation test force (<0.3 N). As the indentation test force increased, the obtained microhardness values decreased faster for the coatings deposited on a softer substrate. The surface roughness impact on wear properties for specific NSC coatings was observed. --//-- This is an open-access article Leitans, A.; Jansons, E.; Lungevics, J.; Kundzins, K.; Boiko, I.; Kanders, U.; Kovalenko, V.; Linins, O. Tribological and Micromechanical Properties of the Nanostructured Carbonitride/Nitride Coatings of Transition Metals Alloyed by Hf and Nb. Coatings 2023, 13, 552. https://doi.org/10.3390/coatings13030552 published under the CC BY 4.0 licence.This research was funded by the Latvian Council of Science, project āCarbon-rich self-healing multifunctional nanostructured smart coatings (NSC) for high-tech applications using high-power confined plasma technology for their depositionā, project No. 2019/1-0385. The Institute of Solid State Physics, University of Latvia at the Center of Excellence has received funding from the European Unionās Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2
