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1

The effect of the amorphous content of laser cladding Ni-Nb-Zr/CaF2 on microstructure and properties

Liang X., Cheng Y., Cheng X., Jiang Y., Kulik T., Ferenc J.

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2018

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no. 4

33--40

EN

Ni-Nb-Zr/CaF2 amorphous coating was prepared on the surface of SA283GRA steel by adopting a high-power laser cladding system. The results show that the Ni-Nb-Zr/CaF2 coating obtained by laser cladding has a good metallurgical bonding with the matrix of SA283GRA and the amorphous phase was obtained. The different amorphous content was obtained with varied laser power. With the increase of laser power, the dilution rate of the coating gradually increases, the amorphous phase content in the cladding coating decreased gradually, and crystallization near the substrate is significant in the laser coating. As the cladding coating is far from the substrate, the content of amorphous phase increases gradually, and the cladding coating has high thermal stability. The hardness of the Ni-Nb-Zr/CaF2 amorphous coating prepared by a laser power of 4 kW is up to the highest value of 890 HV, which is about 4.7 times that of the base material. The electrochemical corrosion results show that the corrosion resistance of the amorphous layer is better than that of the substrate in NaCl solution with 3.5% corrosive medium. The Ni-Nb-Zr/CaF2 laser coating has a relatively strong amorphous forming ability.

PL

Amorficzną powłokę Ni-Nb-Zr/CaF2 otrzymano na powierzchni stali SA283GrA metodą natryskiwania laserowego, z wykorzystaniem laserów dużej mocy. Uzyskane wyniki badań wykazały, że powłoka Ni-Nb-Zr/CaF2 charakteryzuje się dobrą przyczepnością do podłoża stalowego SA283GrA, a faza amorficzna jest otrzymywana w strefie przypowierzchniowej. Wykazano, że moc wyładowania laserowego istotnie wpływa na zawartość fazy amorficznej. Wraz ze wzrostem mocy lasera zawartość fazy amorficznej w strefie przypowierzchniowej zmniejsza się stopniowo, a stopień krystalizacji powłoki w pobliżu podłoża wzrasta. Zawartość fazy amorficznej zwiększa się gradientowo w funkcji odległości od podłoża. Największą twardość powłoki amorficznej Ni-Nb-Zr/CaF2 890 HV uzyskano z wykorzystaniem lasera o mocy 4kW, tj. ≈4,7 razy większą w stosunku do materiału podłoża. Wyniki badań odporności korozyjnej metodą elektrochemiczną wykazały, że w roztworze NaCl z 3,5% odporność na korozję strefy przypowierzchniowej zawierającej fazę amorficzną jest większa niż odporność korozyjna podłoża. Wykazano również, że faza amorficzna Ni-Nb-Zr/CaF2 ma stosunkowo dużą zdolność do formowania się w strefie przypowierzchniowej i charakteryzuje się dużą stabilnością temperaturową.

2

Study on the separation of triterpene saponins from Panax notoginseng by off-line two-dimensional supercritical fluid chromatography–ultrahigh-performance liquid chromatography

Xing Q., Fu Q., Liang X.

Acta Chromatographica

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2017

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Vol. 29, no. 4

497--502

EN

The off-line two-dimensional supercritical fluid chromatography (SFC)–ultrahigh-performance liquid chromatography (UHPLC) was selected to separate the triterpene saponins from Panax notoginseng. The separation by SFC was performed on an Atlantis® HILIC silica column. Methanol was selected as a modifier, and the most time-saving gradient was developed. The decrease of the column temperature and the increase of the back pressure could shorten the retention time but had no effect on the separation selectivity. Then, the back pressure, column temperature, and flow rate were set as 131 bar, 45 °C, and 4.0 mL min−1, respectively. The retention behavior of the saponins from P. notoginseng was different between SFC and reversed-phase liquid chromatography (RPLC), which facilitated to construct an off-line SFC/RPLC–mass spectrometry (MS) system. In first dimension, a total of eight fractions were collected under SFC and further analyzed by RPLC–MS in second dimension. The result indicated that the retention behavior of triterpene saponins was mainly controlled by the hydrogen bonding interactions which were affected by the number and types of sugars, as well as the aglycone in the structure of triterpene saponins. Thus, the presence of “clustering effect” under SFC was observed, namely, one SFC peak always contained several saponins with same number of sugars and similar structure of aglycone. The clustering effect of triterpene saponins promised SFC to be used as first dimension to complete the preliminary crude separation in the two-dimensional liquid chromatography.

3

Effects of cobalt addition on magnetic properties and thermal stability of FeHfBCu-based alloys.

Liang X., Ferenc J., Kowalczyk M., Kulik T., Xu B.

Archives of Materials Science

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2004

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Vol. 25, nr 4

461-467

EN

Nanocrystalline (Fe1-xCox)86Hf7B6Cu1 alloys, where x=0,0.2,0.4,0.5,0.6,0.8 and 1, were investigated as potential magnetically soft materials for high temperature applications. The crystalization process of as-quenched alloys, obtained by melt-spinning technology, was studied by differential thermal analysis (DTA). All alloys crystallize in two stages, occuring between 400 degrees C and 800 degrees C at the heating rate of 20 degrees C/min. Partial of complete replacement of Fe by Co results in a decrease of the 1st and 2nd crystallization stage temperature, T1 and T2 respectively. The enthalpy of secondary crystallization slightly increases with the increase of Co content. The as-quenched ribbons were subjected to isothermal annealing from 300 degrees C to 700 degrees C for 1 hour in vacuum. The optimal annealing temperature, defined as the temperature allowing for the lowest coercive field after annealing, for most of the alloys studied is 550 degrees C. The coercive field of as-quenched and annealed ribbons increases with increasing Co content. In order to study the thermal stability of the magnetic properties, the nanocrystalline alloys were subjected to isothermal annealing at 550 degrees C for a range of time up to 1000 h. The coercive field of alloys with Co content x = or <0.4 is below 50 A/m after annealing for 1000 h.