Prijelom poluge kliješta od čeličnog lijeva GS-42CrMo4

Unsuitable mechanical behaviour of cast steel GS-42CrMo4 (EN) was investigated. In this paper the influence of inclusions and pouring temperature on mechanical properties of arm of carrying jaw made of cast steel GS-42CrMo4 (EN) was investigated. It was found that a high content of aluminium caused the formation of aluminium nitride, AlN which significantly decreased the strength of casting. In the process of solidification, enrichment of lamellas of AlN nitride arise on the grain boundaries. Because of low deformability of AlN nitride, initiation of fracture was possible at minimal deformation. The strength of the casting was not being raised by subsequent heat treatment. High pouring temperature and low cooling rates resulted in coarse-grained microstructure of steel casting. Coarse microstructure was not reduced by subsequent heat treatment.Istraživano je nepovoljno mehaničko ponašanje čeličnog lijeva GS-42CrMo4 (EN). U radu je prikazan utjecaj uključaka i temperature lijevanja na mehanička svojstva poluge kliješta izrađenih od čeličnog lijeva GS-42CrMo4 (EN). Visok sadržaj aluminija uzrokovao je tvorbu aluminijevog nitrida AlN, kojim se bitno umanjila čvrstoća odljevka. Za vrijeme skrućivanja slitine došlo je do obogaćivanja lamela AlN nitrida na granicama kristalnih zrna. Zbog male deformabilnosti AlN nitrida, do iniciranja prijeloma došlo je već kod minimalne deformacije. Čvrstoća odljevka nije se povećala naknadnom toplinskom obradom. Visoka temperatura ulijevanja prouzrokovala je grubozrnatu strukturu. Grubozrnata struktura nije se usitnila naknadnom toplinskom obradom

THE POSSIBILITY OF APPLYING NEAT METALWORKING OILS FOR CYLINDER LINER HONING

Sažetak Honanje ili vlačno glačanje je postupak kojim obrađujemo najfinije površine metala radi postizanja zahtijevane točnosti i kvalitete obrađenih površina. Samo honanje kao i procesi struganja, glodanja, brušenja, tj. rezno uobličavanje metalnih materijala u svom se djelovanju ograničava na relativno tanak površinski sloj izratka i uglavnom izaziva hladnu plastičnu deformaciju, ali ne utječe dalekosežno na strukturu i svojstva materijala. Pri izvođenju procesa honanja vrlo je bitno da se radna površina oplahuje znatnim količinama sredstava za hlađenje i podmazivanje. Radnu površinu valja hladiti da ne bi došlo do promjene strukture zbog procesa rekristalizacije i otpuštanja. Osim toga, ispiranjem se odvodi metalna prašina nastala honanjem te iščupana zrnca s bruseva. Danas su istraživanja na ovom području usmjerena na primjenu novih sredstava za hlađenje i podmazivanje. Na temelju ekonomske i ekološke analize i analize kvalitete postupka honanja pri primjeni sredstava za hlađenje i podmazivanje na osnovi mineralnih ulja i uz sadržaj različitih tipova aditiva, u radu je ispitivana mogućnost primjene novih ulja pri honanju košuljica cilindara.Abstract Honing is a procedure treating the finest metal surfaces in order to achieve the required precision and quality of treated surfaces. Honing itself, as well as proceses of grating, milling, grinding, i.e. using cutting for the shaping of metal materials, is in its activity limited to a relatively thin surface layer of the workpiece, mostly causing cold plastic deformation, without any long-term impacts on either the structure or properties of the material. When performing the process of honing, it is extremely important that the working surface be washed by considerable volumes of the cooling and lubrication agents. The working surface needs to be cooled, so as not to cause any structural change due to the processes of recrystallization and release. Apart from that, rinsing takes away the metal dust generated by honing, as well as the pulled out grinding wheel grains. Research in this area is today oriented towards applying new cooling and lubricating agents. Based on economic and environmental analysis, as well as that of the quality of honing procedure when applying cooling and lubricating agents based on mineral oils, containing various types of additives, the paper also considers the possibility of applying new oils for the honing of cylinder bores

Potentiometric Surfactant Sensor Based on 1,3-Dihexadecyl-1H-benzo[d]imidazol-3-ium for Anionic Surfactants in Detergents and Household Care Products

A 1, 3-dihexadecyl-1H-benzo[d]imidazol-3-ium- tetraphenylborate (DHBI-TPB) ion-pair implemented in DHBI-TPB surfactant sensor was used for the potentiometric quantification of anionic surfactants in detergents and commercial household care products. The DHBI-TPB ion-pair was characterized by FTIR spectroscopy and computational analysis which revealed a crucial contribution of the C–H∙∙∙π contacts for the optimal complex formation. The DHBI-TPB sensor potentiometric response showed excellent analytical properties and Nernstian slope for SDS (60.1 mV/decade) with LOD 3.2 × 10−7 M ; and DBS (58.4 mV/decade) with LOD 6.1 × 10−7 M was obtained. The sensor possesses exceptional resistance to different organic and inorganic interferences in broad pH (2–10) range. DMIC used as a titrant demonstrated superior analytical performances for potentiometric titrations of SDS, compared to other tested cationic surfactants (DMIC > CTAB > CPC > Hyamine 1622). The combination of DHBI-TPB sensor and DMIC was successfully employed to perform titrations of the highly soluble alkane sulfonate homologues. Nonionic surfactants (increased concentration and number of EO groups) had a negative impact on anionic surfactant titration curves and a signal change. The DHBI-TPB sensor was effectively employed for the determination of technical grade anionic surfactants presenting the recoveries from 99.5 to 101.3%. The sensor was applied on twelve powered samples as well as liquid-gel and handwashing home care detergents containing anionic surfactants. The obtained results showed good agreement compared to the outcomes measured by ISE surfactant sensor and a two-phase titration method. The developed DHBI-TPB surfactant sensor could be used for quality control in industry and has great potential in environmental monitoring

Direct Potentiometric Study of Cationic and Nonionic Surfactants in Disinfectants and Personal Care Products by New Surfactant Sensor Based on 1,3-Dihexadecyl−1<i>H</i>-benzo[<i>d</i>]imidazol−3-ium

A novel, simple, low-cost, and user-friendly potentiometric surfactant sensor based on the new 1,3-dihexadecyl−1H-benzo[d]imidazol−3-ium-tetraphenylborate (DHBI–TPB) ion-pair for the detection of cationic surfactants in personal care products and disinfectants is presented here. The new cationic surfactant DHBI-Br was successfully synthesized and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectrometry, liquid chromatography–mass spectrometry (LC–MS) and elemental analysis and was further employed for DHBI–TPB ion-pair preparation. The sensor gave excellent response characteristics for CTAB, CPC and Hyamine with a Nernstian slope (57.1 to 59.1 mV/decade) whereas the lowest limit of detection (LOD) value was measured for CTAB (0.3 × 10−6 M). The sensor exhibited a fast dynamic response to dodecyl sulfate (DDS) and TPB. High sensor performances stayed intact regardless of the employment of inorganic and organic cations and in a broad pH range (2−11). Titration of cationic and etoxylated (EO)-nonionic surfactant (NSs) (in Ba2+) mixtures with TPB revealed the first inflexion point for a cationic surfactant and the second for an EO-nonionic surfactant. The increased concentration of EO-nonionic surfactants and the number of EO groups had a negative influence on titration curves and signal change. The sensor was successfully applied for the quantification of technical-grade cationic surfactants and in 12 personal care products and disinfectants. The results showed good agreement with the measurements obtained by a commercial surfactant sensor and by a two-phase titration. A good recovery for the standard addition method (98–102%) was observed