Laboratory Heat Treatment of the Shell Material of the Centrifugally Cast Roll for the Last Finishing Stand of Hot Strip Mills

The rolls for the hot rolling finishing stands are cast centrifugally as two or three-layer rolls. The working layer is called a shell. The material of the shell is selected according to the position of the respective roll in the final finishing stand of the rolling mill. Typically, a combination of rolls made of a high-chromium cast iron + indefinite cast iron or high-speed steel + indefinite cast iron is commonly used. Great attention has been paid to indefinite cast iron in recent years and this material received a number of modifications that led to the increase of material properties up to 20% in comparison to the ordinary indefinite cast iron. But the goals of the new generation of material for hot rollers were chosen higher: increasing of production about 30% and more. This material has specific physical properties, heat treatment requirements as well as rolling mill requirements as is stated in the paper. It is expected that introduction of this material will reduce the difference between wear of the front and finishing stands, which can extend rolling campaigns and have a positive effect on the reduction rolls exchanges, the grinding of the rolls and the reduction of downtime

Historic Mortars:Characterisation, Assessment and Repair

This volume focuses on research and practical issues connected with mortars on historic structures. The book is divided into four sections: Characterisation of Historic Mortars, Repair Mortars and Design Issues, Experimental Research into Properties of Repair Mortars, and Assessment and Testing. The papers present the latest work of researchers in their field. The individual contributions were selected from the contributions to the 2nd Historic Mortars Conference, which took place in Prague, September, 22-24, 2010. All papers were reviewed and improved as necessary before publication. This peer review process by the editors resulted in the 34 individual contributions included in here. One extra paper reviewing and summarising State-of-the-Art knowledge covered by this publication was added as a starting and navigational point for the reader. The editors believe that having these papers in print is important and they hope that it will stimulate further research into historic mortars and related subjects.

Composition and Technology of the 17th Century Stucco Decorations at Červená Lhota Castle in the Southern Bohemia

The stucco decoration from the Great Chamber of the castle Červená Lhota in the Southern Bohemia was surveyed and characterised as part of its planned conservation. The repair works that are still to be specified in detail should be based on a good knowledge of the original material and technique. The main focus was on the fruit pieces decorating the ribs of vaults. Altogether, over twenty mortar samples were collected from the vault bedding mortar, plaster, drawn elements and stuccos. Additionally, some pieces of fruits, that were loose and had to be temporarily removed, were studied macroscopically and by X-ray CT. Characterisation of binder, aggregate and additives was carried out using TA, acid attack, sieve analysis of unsolvable residue, XRD, FTIR and nL-MS. The characterisation led to understanding of the uses of various mortar mixes and determination of their recipes. A typical fruit piece was composed of an inner modelling core mortar made of lime-gypsum binder and a coarser aggregate covered with a 5–20 mm think lime rich stucco layer containing calcitic air lime and fine siliceous sand. This stucco mortar was also used for modelling various small decorations - fine and thin shapes like leaves, cherries and grapes. These were attached to the main piece by a fine adhesive mortar made of lime and gypsum in various proportions. The use of gypsum and the differences in lime to gypsum ratio corresponded to a certain functional requirements (performances). This finding was a key parameter that contributed to the reconstruction of the original application technique and procedure. Qualitative analysis of animal proteins determined presence of collagen – an animal glue that was used to modify the setting of gypsum and which was also used in the final finish. The results are discussed as an example of a procedure that aims at a detailed replication of the original technique