1,721,025 research outputs found
Instant ecological pickling on stainless steel welds and innovative surface passivation
No full textThe aim of this work is to improve the innovative process for pickling and passivating stainless steel welds and surfaces in order to obtain complete removal of non-protective oxides and to restore the passivation. The treatment, based on an electrochemical principle, uses specific electrolytes and patented electrodes: the advantage is to increase the corrosion resistance, working speed (instant process) and surface appearance on stainless steel, avoiding the traditional pickling solutions (which usually contain high concentrations of strong and toxic acids). Different solutions were prepared using low concentrations of weak organic acids, e.g. citric, oxalic, sulphamic, gluconic and lactic, up to the new neutral (pH 7, acid free) solution used to gain high passivation on stainless steel surfaces. This aspect is very important to reduce the hazardousness of the solution compared to the pure phosphoric acid (standard solution) and moreover to the traditional pickling acids. The best solutions in terms of aesthetic result were tested in terms of corrosion resistance (free and accelerated) XPS analysis, on TIG and MIG samples. A S.E.M. analysis is used to show the influence of the carbon fiber effect depending on the technology used (transformer vs inverter) and electrolyte. A number of real field application is presented, both manual and custom/automation
Electrochemical marking for instant permanent decoration of stainless steel surfaces
No full textThe aim of this work is to study the electrochemical marking process that allows to obtain technical and decorative graphical effects on stainless steel by the controlled growth of protective oxides and to develop new electrolytes able to increase even more the technical and aesthetic result on different stainless steels series. The advantages of the electrochemical marking are: i) the possibility to obtain decorations with greater mechanical and chemical resistance compared to those obtained by screen printing and laser processes; ii) high process speed (few seconds); iii) the absence of heat input to the treated surface, unwelcome phenomenon that, in the case of laser marking, may lead to the deformation of the artifacts in particular on low sheet thicknesses or when realizing big logos; iv) high graphical definition; v) ecology: no solvents, acids or dangerous compounds needed; vi) low power consumption: possibility to use portable battery powered units. In particular, the aim of this work is to characterize the oxides obtained by electrochemical decoration on EN 1.4301/AISI 304 austenitic stainless steel in terms of corrosion resistance (by polarization curves), chemical composition (by Raman spectroscopy) and color (CIE Lab visible spectroscopy). The results obtained from the characterization were then used to formulate new compositions of the electrolyte that allow to improve the process (more black) but especially to create a specific electrolyte to treat different series of stainless steels, such as ferritic (e.g.: AISI 430) and austenitic manganese (e.g.: AISI 202) . This oxide presents a compact structure capable of giving excellent corrosion resistance and grows improving the chromium oxide naturally present on the surface of stainless steel. The black color of the marking oxide also guarantees excellent results from the aesthetic point of view, providing a high contrast with the stainless surface, not only on standard applications (company logo, data plates, codes, etc.) but also on large surface decorations for design and architecture purposes
Effect of temperature on pulsed current chromium electrodeposition from Cr(III) aqueous solutions
No full textChromium electrodeposition is widely used industrially to obtain protective coatings with high corrosion resistance combined with other important properties such as high hardness and wear resistance (hard chromium plating) or high surface finishing (decorative chromium plating).In recent years, much attention was given to finding alternative electroplating methods that could achieve similar coatings without the use of hexavalent chromium, given the known toxicity of its compounds. Ideally the deposition of metallic chromium from trivalent chromium acqueous solutions represent the easier strategy to obtain such coatings without the use of hazardous solutions; unfortunatelly a lot of complications concerning the chemistry of trivalent chromium in acqueous solution make this way very difficult to pursue. In this work some deposition strategies have been developed, obtaining; on carbon steel substrate, metallic chromium coatings with good properties (high adhesion to the substrate, micro-hardness, surface finishing) starting from aqueous solutions of Cr (III) and formic acid. The developed strategies are based on the use of pulsed current (and optimization of its process parameters, such as duty cycle, period and magnitude of current applied) and low temperatures
Studio del bilancio energetico in quattro rotazioni colturali eseguite per un dodicennio con diversi livelli di concimazione e di irrigazione. Nota 1: energia della sostanza secca prodotta e del prodotto agrario utile.
No full textStudio del bilancio energetico in quattro rotazioni colturali eseguite per un dodicennio con diversi livelli di concimazione e di irrigazione. Nota II: energia contenuta nel cibo per l'uomo.
No full textPulizia in linea del filo metallico su impianti di trafilatura ad alta velocità: Innovazione, ecologia e performance
No full textNei processi di trafilatura il filo metallico subisce una sequenza di passaggi forzati attraverso matrici (filiere), di diametro decrescente,
che ne riducono progressivamente la sezione fino al valore desiderato. Per assicurare il passaggio attraverso le filiere, riducendo
quanto più possibile l’attrito, è necessaria una lubrificazione, ottenuta tramite l’utilizzo di diverse sostanze chimiche: si passa da
emulsioni acqua/olio per lubrificazione liquida, a stearati di sodio e/o calcio o polimeri per lubrificazione solida. Tali lubrificanti
devono formare un film sottile, omogeneo e ben adeso al filo, ma devono poter essere rimossi al termine dei processi di riduzione
di sezione se si desidera ottenere un filo superficialmente pulito e pronto per eventuali successivi trattamenti galvanici, termici o
di rivestimento superficiale di vario genere. In questo articolo verrà analizzata una tecnica innovativa per la pulizia del filo, in linea
con l’impianto di trafilatura, applicabile sia a monte del processo (pulizia/decapaggio della vergella) sia a valle (pulizia finale prebobinatura).
La tecnica in esame, basata su un processo elettrochimico, può essere integrata su linee già esistenti e va a sostituire le vasche
chimiche o ad ultrasuoni di pulizia post-trafilatura, facendo uso di elettroliti a minor impatto ambientale rispetto ai tradizionali
liquidi per sgrassaggio acido e alcalino
Proprietà fisiche del terreno, accrescimento e resa di una coltura di mais (Zea mais) allevata su arginelli permanenti
No full textConfronto tra sistemi colturali a diverso input energetico in zone prevalentemente maidicole della media pianura friulana.
No full textNITROGEN FERTILIZATION IN WET AND DRY CLIMATE
No full textFertilization may help crops to yield better. To determine whether meteorological
and
soil
conditions
influence
the
productive
response
of nitrogen
fertilization
in
sunflower,
a study
was
conducted
in
an Italian
interregional
project
(BIOLI). The effects
of nitrogen
fertilization
on
two
commercial
higholeic
varieties
(Carnia
and
PR 64 H 61) was
investigated
in
North
East
(Udine)
and
East
Central
Italy
(Osimo)
during
2005.
Nitrogen
fertilization
was
not
effective
in
Osimo
under
rainfed
and
drought
conditions,
whereas
the
highest
N
level
gave the
best
yield
in
Udine
in
wet
and
irrigated
conditions.
In both
locations
plant
size
was positively
influenced
by fertilization.
No differences were observed among varieties in Osimo, whereas in Udine
the locally selected hybrid had the best performance. Nitrogen fertilization is
suggested only in good weather conditions and in nitrogen poor soil. Under
drought conditions nitrogen influences plant growth but not yield
Ricerca sperimentale sull'impiego di Cannabis sativa L. nella fitoestrazione di metalli pesanti
No full text- …
