Utilización de chamota posconsumo en la formulación de una pasta refractaria como sustitución de la alúmina

O desenvolvimento de materiais cerâmicos refratários é derivado de indústrias que utilizam altas temperaturas em seus processos. O uso de material pós-consumo para a formulação de pastas refratárias é de interesse para o desenvolvimento sustentável com impacto econômico e ambiental. O objetivo deste trabalho é estudar o efeito da adição de chamotte pós-consumo em uma pasta refratária como substituição de alumina. A chamotte foi obtida a partir de tijolos isolantes refratários porosos que cumpriram seu ciclo de vida na indústria cerâmica. Estes foram submetidos a um processo de trituração usando um moinho de bolas até passar pela malha 50. A chamotte foi caracterizada por difração de raios X. Quatro misturas foram formuladas e sinterizadas a 1600 °C. Foram avaliados cone cromático (ASTM C-24), densidade e porosidade (ASTM C-20), contração linear e dilatometria. Os resultados indicam que a adição de chamotte pós-consumo reduz o cone pirrométrico do refratário obtido, a amostra que não contém chamotte tem um cone maior que 36 e a amostra de maior conteúdo possui um cone de 32, adequado para uso como tijolo refratário Com a adição de chamotte, a densidade das amostrasaumentou e a porosidade e contração diminuíram. Finalmente, no teste de dilatometria, são evidenciadas alterações na curva dilatométrica, atribuídas a uma maior formação de fase  líquida e finas devido à contribuição da sílica e do K2O presente na chamotte.El desarrollo de los materiales cerámicos refractarios ha sido derivado de las industrias que utilizan altas temperaturas en sus procesos. El uso de material posconsumo para la formulación de pastas refractarias es de interés para el desarrollo sostenible con impacto económico y ambiental. El objetivo de este trabajo es estudiar el efecto de la adición de chamota posconsumo en una pasta refractaria como reemplazo de alúmina. La chamota fue obtenida a partir de ladrillos aislantes refractarios porosos que cumplieron su ciclo de vida en la industria cerámica. Estos fueron sometidos a un proceso de conminución utilizando un molino de bolas hasta llevarlo a pasante malla 50. La chamota se caracterizó mediante Fluorecencia de rayos X. Se formularon cuatro mezclas y se sinterizaron a 1600 ºC. Se evaluó el cono pirométrico (ASTM C-24), la densidad y la porosidad (ASTM C-20), la contracción lineal y dilatometría. Los resultados indican que la adición de chamota posconsumo disminuye el cono pirométrico del refractario obtenido; la muestra que no contiene chamota tiene un cono superior a 36 y la muestra de mayor contenido tiene un cono de 32, los cuales son adecuados para el uso como ladrillo refractario. Con la adición de chamota se aumentó la densidad de las muestras y se disminuyó la porosidad y la contracción. Finalmente, en el ensayo de dilatometría se evidencian cambios en la curva dilatometría que se atribuyen a una mayor formación de fase líquida y mulita, debido al aporte que hace la sílice y el K2O presentes en la chamota.The development of refractory ceramic materials has been derived from industries that use high temperatures in their processes. The use of post-consumer material for the formulation of refractory pastes is of interest for sustainable development with economic and environmental impact. The objective of this work is to study the effect of the addition of post-consumption chamotte in a refractory paste as an alumina replacement. The chamotte was obtained from porous refractory insulating bricks that fulfilled their life cycle in the ceramic industry. These were subjected to a comminution process using a ball mill until it was passed through 50 mesh. The chamotte was characterized by X-ray diffraction. Four mixtures were formulated and sintered at 1600 °C. Pyrometric cone (ASTM C-24), density and porosity (ASTMC-20), linear contraction and dilatometry were evaluated. The results indicate that the addition of postconsumption chamotte reduces the pyrometric cone of the refractory obtained, the sample that does not contain chamotte has a cone over 36 and the sample of higher content has a cone 32, which are suitable for use as a refractory brick. With the addition of chamotte, the density of the samples was increased and the porosity and contraction decreased. Finally, in the dilatometry test, changes in the dilatometric curve are evidenced, which are attributed to a greater formation of liquid phase and fines due to the contribution made by silica and K2O present in the chamotte

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe

Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV

We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.Peer reviewe

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The second-order Fourier coefficients (v(2)) characterizing the azimuthal distributions of Y(1S) and Y(2S) mesons produced in PbPb collisions at root s(NN) = 5.02 TeV are studied. The Y mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb(-1). The scalar product method is used to extract the v2 coefficients of the azimuthal distributions. Results are reported for the rapidity range vertical bar y vertical bar < 2.4, in the transverse momentum interval 0 < pT < 50 GeV/c, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/psi mesons, the measured v(2) values for the Y mesons are found to be consistent with zero. (C) 2021 The Author(s). Published by Elsevier B.V.Peer reviewe