Search results for "PRESSING"

Forming pressure dependence of the ferroelectric domain structure in green barium titanate pellets

1995

Abstract Modifications of the X-ray diffraction line profiles by die pressing of fine grained powders of barium titanate have been studied. Two main parameters have been considered: the forming pressure and the mechanical characteristics of the binder. The higher the forming pressure, the greater the modifications of the line profiles. Furthermore, the phenomena seems to be related to pressing only; no significant effect related to the nature of the binder has been shown. The modifications of the diffraction line profiles are interpreted by considering a reduction of the size of the ferroelectric domains during pressing. In order to confirm this interpretation, the behaviour of the domain s…

Study of new joining technique: flat clinching

2007

In this paper a development of clinching, called flat clinching, is presented. After a press clinching process, the joined sheets have been deformed by a punch with a lower diameter against a flat die. In this way a new configuration is created with a geometry that has no discontinuity on the external surface (bottom). A new procedure has also been tested: the second step is perfomed by pressing the joint between two flat dies. This second case has revealed itself to be very effective.Tensile tests have been done to compare the joints strength among the various joining techniques. Moreover some joints have been cut to analyse the changing of the contact line shape and how its characteristic…

Dry content analysis in wet pressing: Sensitivity to pressing variables

2002

Aging of MCM41, MSU-H and MSU-F mesoporous systems investigated through the Raman spectroscopy

2014

Here we report an experimental investigation, based on the Raman spectroscopy, on the aging of some mesoporous silica based systems. In details, we studied the aging in air of the MCM41, the MSU-H and the MSU-F materials by acquiring the Raman spectra of as received and of mechanically pressed, at 0.2 and 0.45 GPa, powders. Our data evidenced that the starting powders of the MCM41 and of the MSU-H undergo structural modification when they are exposed to the ambient atmosphere, such modification consisting in the decrease of the D2 Raman band (originated by the three member rings). At variance the powders of the MSU-F appear to be stable. Furthermore, by pressing the starting powders to prod…

Severe plastic deformation (SPD) processes for metals

2008

Abstract Processes of severe plastic deformation (SPD) are defined as metal forming processes in which a very large plastic strain is imposed on a bulk process in order to make an ultra-fine grained metal. The objective of the SPD processes for creating ultra-fine grained metal is to produce lightweight parts by using high strength metal for the safety and reliability of micro-parts and for environmental harmony. In this keynote paper, the fabrication process of equal channel angular pressing (ECAP), accumulative roll-bonding (ARB), high pressure torsion (HPT), and others are introduced, and the properties of metals processed by the SPD processes are shown. Moreover, the combined processes …

How to reduce energy and water consumption in the preparation of raw materials for ceramic tile manufacturing: Dry versus wet route

2017

Abstract Dry and wet routes in the ceramic tile manufacturing process refer to two different technologies for preparing the raw materials for the forming stage. Both result in a granulated solid ready for use in the pressing stage, but with different characteristics. The dry route was the first to be developed. As quality standards and tile sizes increased, the wet route was developed and introduced successfully into the manufacturing process. Since 1990, the wet route has been the most used around the world to prepare ceramic tile body raw materials. The powder produced by the wet route has finer particles and higher flowability, which has allowed the production of higher quality ceramic t…

High chromium-carbon’s steel microstructural and properties evolutions after Hot Isostatic Pressing (HIP) process : From powder to final product.

2021

Fe-Cr-C alloys are frequently used as hard coating coatings for nuclear valves in pressurized water reactors (PWRs), due to their good mechanical resistance and corrosion. The Norem02 alloy (Fe - 25% Cr - 4% Ni - 4% Mn - 4% Si - 2% Mo) is one of the most promising candidates. Hardfacing coatings are typically deposited by a plasma transferred arc welding (PTAW) process, which results in a coarse and heterogeneous microstructure, exhibiting unsatisfactory wear resistance properties, mainly at high temperature. In the present study, Norem02 is developed by Hot Isostatic Compression (CIC), a pressure assisted sintering technique where a powder is placed in a plastically deformable container un…

Interactions between Streptococcus thermophilus and thermophilic lactobacilli strongly affect its growth during pressing of swiss-type cheeses

2007

National audience

Hydraulic kinetics of the graft union in different Olea europaea L. scion/rootstock combinations

2007

The hydraulic resistance of young olive trees grafted on rootstocks with contrasting size-controlling potential was measured 30, 90, 360 and 480 days after grafting. Olive (Olea europaea L.) clones inducing plant vigorous growth (Leccino ‘Minerva’, LM) or dwarfing (Leccino ‘Dwarf’, LD) were studied in different scion/rootstock combinations (LD/LD, LD/LM, LM/LD, LM/LM). Plants growing on LD root systems developed lower leaf surface areas (about 50% less) than plants grafted on LM rootstocks. Graft union represented the largest fraction (up to 85%) of whole-plant hydraulic resistance 30 days after grafting, and still represented an important fraction of it 2 months later (40–55%). Four-hundre…

On the use of ionic liquids as mobile phase additives in high-performance liquid chromatography. A review.

2015

The popularity of ionic liquids (ILs) has grown during the last decades in several analytical separation techniques. Consequently, the number of reports devoted to the applications of ILs is still increasing. This review is focused on the use of ILs (mainly imidazolium-based associated to chloride and tetrafluoroborate) as mobile phase additives in high-performance liquid chromatography (HPLC). In this approach, ILs just function as salts, but keep several kinds of intermolecular interactions, which are useful for chromatographic separations. Both cation and anion can be adsorbed on the stationary phase, creating a bilayer. This gives rise to hydrophobic, electrostatic and other specific in…