575 research outputs found
Zaštitna aluminijska prevlaka izvedena izravno u ljevačkom kalupu na čeliku otpornom prema puzanju
The structure of coatings and their ability to protect the castings made of G-X25NiCrSi 36-17 (DIN 17006) cast steel against carburization have been described. Al-Cu and Al-Si protective coatings, produced directly in a casting mould, have a considerable thickness (400 - 2000 µm), and complex multiphase structure. Its main structural constituents are: (Fe, Ni, Cr), (Fe, Ni, Cr), Al(Ni, Fe), carbides M23C6 and M7C3. In Al-Si ferritic coatings are also present: (Ni, Fe), (Fe, Al, Ni, Cr) and (Cr, Si)3Ni2Si. Carburisation changes substantially the structure of coatings, what results in an increase of the amount of (Fe, Ni, Cr) or (Ni, Fe) and carbides, and a decrease of the amount of (Fe, Ni, Cr) and Al(Ni, Fe). Apart from above mentioned changes, the investigated coatings reduce the carbon diffusion by 20 - 65 % Al-Cu, about 55 % Al-Si (austenitic), and 75 % Al-Si (ferritic), so they can provide a temporary protection against high-temperature corrosion.U radu je opisana struktura prevlaka i njihova sposobnost lijevanja od G-X25NiCrSi 36-17 (DIN 17006) u svrhu zaštite protiv naugljičavanja. Zaštitne prevlake Al-Cu i Al-Si, napravljene izravno u ljevačkom kalupu, imaju znatnu debljinu (400 - 2000 µm) i složenu multifaznu strukturu. Glavni strukturni element su: g(Fe, Ni, Cr), a(Fe, Ni, Cr), bAl(Ni, Fe), karbidi M23C6 i M7C3. U feritnim prevlakama Al-Si prisutni su i: g(Ni, Fe), a(Fe, Al, Ni, Cr) i (Cr, S)3Ni2Si. Naugljičavanje mijenja suštinu strukture prevalaka, a to dovodi do povećanja količine g(Fe, Ni, Cr) ili g(Ni, Fe) i karbida, a smanjuje količinu a(Fe, Ni, Cr) i bAl(Ni, Fe). Neovisno o gore spomenutim promjenama prevlake smanjuju difuziju ugljika za 20-60 % Al-Cu, oko 55 % Al-Si (austenitni) i 75 % Al-Si (feritni) pa mogu osigurati privremenu zaštitu protiv korozije na visokoj temperaturi
2-Chloro-N-[4-chloro-2-(2-chlorobenzoyl)phenyl]acetamide
In the title compound, C15H10Cl3NO2, an intramolecular N—H⋯O hydrogen bond forms a six-membered ring and enforces an almost coplanar conformation for the acetamido group, the central benzene ring and the bridging carbonyl C—C(=O)—C group: the dihedral angles between the benzene ring and the acetamide and carbonyl C—C(=O)—C planes are 7.06 (11) and 7.17 (12)°, respectively. The dihedral angle between the two benzene rings is 67.43 (9)°. Because a strong hydrogen-bond donor is involved in the intramolecular interaction, the crystal packing is determined by weak C—H⋯O and C—H⋯Cl interactions
Tramadolium picrate
In the title salt {systematic name: [2-hydroxy-3-(3-methoxyphenyl)cyclohexylmethyl]dimethylazanium 2,4,6-trinitrophenolate}, C16H26NO2
+·C6H2N3O7
−, the cation is protonated at the N atom. The cyclohexane ring adopts a chair conformation with the hydroxy substituent in an axial position. In the crystal, O—H⋯O and N—H⋯O hydrogen bonds link the cations and anions into supramolecular chains along [100]
(1RS,6SR)-Ethyl 4,6-bis(4-fluorophenyl)-2-oxocyclohex-3-ene-1-carboxylate
In the crystal structure of the title compound, C21H18F2O3, the cyclohexene ring has a slightly distorted sofa conformation; the two benzene rings are inclined by 76.27 (8)° and their planes make dihedral angles of 16.65 (10) and 67.53 (7)° with the approximately planar part of the cyclohexenone ring [maximum deviation 0.044 (2) Å, while the sixth atom is displaced by 0.648 (3) Å from this plane]. In the crystal, weak intermolecular C—H⋯O, C—H⋯F and C—H⋯π interactions join molecules into a three-dimensional structure
(1RS,6SR)-Ethyl 4-(4-chlorophenyl)-6-(4-fluorophenyl)-2-oxocyclohex-3-ene-1-carboxylate toluene hemisolvate
In the crystal structure of the title compound, C21H18ClFO3·0.5C7H8, the toluene solvent molecules occupy special positions on centres of symmetry, and consequently are disordered across this site. The cyclohexene ring has a slightly distorted sofa conformation; the two benzene rings are inclined by 72.90 (7)° and their planes make dihedral angles of 30.09 (10) (chlorophenyl) and 88.13 (6)° (fluorophenyl) with the approximately planar part of the cyclohexenone ring [maximum deviation from plane through five atoms is 0.030 (2) Å, the sixth atom is 0.672 (3)Å out of this plane]. Weak intermolecular C—H⋯O and C—H⋯X (X = F, Cl) interactions join molecules into a three-dimensional structure. Also, a relatively short and directional C—Cl⋯F—C contact is observed [Cl⋯F = 3.119 (2) Å, C—Cl⋯F = 157.5 (2)° and C—F⋯Cl 108.3 (2)°]. The solvent molecules fill the voids in the crystal structure and are kept there by relatively short and directional C—H⋯π interactions
(E)-3-(4-Chlorophenyl)-1-(1-naphthyl)prop-2-en-1-one
In the title compound, C19H13ClO, the benzene ring and the naphthalene system, are twisted by 12.3 (3) and 36.1 (2)°, respectively, and in opposite directions with respect to the central propenone bridge. The bond-angle pattern within the benzene ring is influence by both substituents; these influences are almost additive. In the crystal, the molecules are linked by C—H⋯O and C—H⋯Cl interactions
1-Methylpiperazine-1,4-diium dipicrate
In the crystal structure of the title compound [systematic name: 1-methylpiperazine-1,4-diium bis(2,4,6-trinitrophenolate)], C5H14N2
2+·2C6H2N3O7
−, the ionic components are connected by relatively strong N—H⋯O hydrogen bonds into centrosymmetric six-membered conglomerates, which comprise two dications and four anions. Besides Coulombic interactions, only weak C—H⋯O interactions and some stacking between picrates (separation between the planes of ca. 3.4 Å but only a small overlapping) can be identified between these ‘building blocks’ of the crystal structure. The piperazine ring adopts a chair conformation with the methyl substituent in the equatorial position. In the picrate anions, the twist angles of the nitro groups depend on their positions relative to the phenolate O atom: it is much smaller for the NO2 groups para to the C—O− group [15.23 (9)and 3.92 (14)°] than for the groups in the ortho positions [28.76 (13)–39.84 (11)°]
(2E)-1-(4-Bromophenyl)-3-(4-fluorophenyl)prop-2-en-1-one
The title compound, C15H10BrFO, is isostructural with (2E)-1-(4-chlorophenyl)-3-(4-fluorophenyl)prop-2-en-1-one [Qiu et al. (2006 ▶). Acta Cryst. E62, o3525–o3526], but the structures of other dihalogen analogues, without fluorine, are different, although they are also isostructural within the series. The molecule is approximately flat, the dihedral angle between the ring planes being 8.49 (13)°. In the crystal structure, intermolecular C—H⋯O, C—H⋯F and C—H⋯Br hydrogen bonds link molecules into V-shaped ribbons running parallel to [101] and stacked with an interplanar distance of approximately 3.53 Å (centroid–vcentroid distance = 3.857 Å).
(1RS,6SR)-Ethyl 4-(2,4-dichlorophenyl)-6-(4-fluorophenyl)-2-oxocyclohex-3-ene-1-carboxylate
There are two symmetry-independent molecules in the asymmetric unit of the title compound, C21H17Cl2FO3. Both these molecules are very similar: the normal probability plots for bond lengths, angles and even for torsion angles show that the differences are of a statistical nature. A pseudocentre of symmetry is located between the symmetry-independent molecules at [0.245 (1), 0.535 (19), 0.909 (1)]. The cyclohexene rings have slightly distorted sofa conformations in both molecules and the two benzene rings are inclined by dihedral angles of 61.33 (14) and 62.85 (14)°. In the crystal, relatively short intermolecular C—H⋯O interactions join molecules into homomolecular (i.e. ⋯AAA⋯ and ⋯BBB⋯) chains along the b axis. These chains are interconnected by further heteromolecular C—H⋯O interactions
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