Diamante A&T Contents
Issue 102

Year XXVI - December 2020

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Front Cover: POLIGEM SRL
Via Ernesto Rizzi 13/p, 20077 Melegnano (MI), Italy

Poligem is a private independent company that has been a leader in the superabrasive market since 1996. Thanks to the experience accumulated in the synthesis, selection and grinding of the diamond, Poligem has been for years a constant presence in Europe in the tools, abrasives and non-conventional diamond applications sectors. From natural diamond to synthetic diamond, from polycrystalline diamond to Cubic Boron Nitride, Poligem is able to respond with the best solution to the needs of the industry.

www.poligem.it




In the Spotlight

08) The importance of renewing rather than replacing: with GlassRenu glass surfaces come back perfect

12) A life in diamond. DIAVIT Srl case history

14) Let me introduce Diamant: craftsmanship and technology




Diamond Tools

17) Development of Powder Injection Moulding process of cobalt free diamond composite for cutting tool applications

by I. Agote1, C. Guraya1, A. Colella2, E. Nicolis3, M. Dai Prč3
1 Tecnalia, Basque Research and Technology Alliance (BRTA), Donostia/San Sebastián, Spain
2 MBN Nanomaterialia S.p.A, Vascon di Carbonera (TV), Italy
3 Dellas S.p.A, Lugo di Grezzana (VR), Italy

Abstract: Nowadays, diamond blades and wires are commonly used for sawing natural stone, concrete and ceramics. The cutting section of the tool consists of synthetic diamond crystals embedded in a metallic matrix, obtained using powder metallurgical (PM) routes: the most common route includes the hot pressing of the composite to obtain a fully dense part. This process has some limitations in terms of achievable part geometrical complexity and process productivity. In addition, the most commonly used metallic matrix is cobalt, which besides its proven high toxicological risk (REACH legislation), it is considered as a critical raw material (CRM) by the European Union. The present work has a twofold objective: from one side the substitution of cobalt by other non-toxic elements, and at the same time, the development of a powder injection moulding process to allow obtaining more complex shape parts (thus improving their performance) and increasing the process productivity.



Industrial Diamond

26) Quality analysis methods of synthetic diamonds for industrial use - Part II

by P. Lubatti, Poligem Srl

Abstract: In this paper the author focuses on some aspects related to the methods of analysis previously described in the article "Quality analysis methods of synthetic diamonds for industrial use" (Diamante A&T nr 100, pag.40-44), in order to clarify what impact these methods of analysis can have on the tools performance.



32) Investigations of microcracks on arranged diamonds with X-ray microscopy

by W. Tillmann1, D. Biermann2, C. Muller3, M. Ferreira1, M. Kansteiner2, J. Dreier2
1 Institute of Materials Engineering, TU Dortmund, Germany
2 Institute of Machining Technology, TU Dortmund, Germany
3 Statistics with Application in Engineering Sciences, TU Dortmund, Germany

Abstract: Powder metallurgically fabricated diamond-metal composites shaped into small segments for circular saws and core drilling bits are state of the art for cutting and grinding concrete and natural stone. Current manufacturing approaches focus on the controlled positioning of the diamond grains in the cutting segments. This fabrication method allows easy adaption of the cutting tools to achieve higher cutting performance, reproducibility and the possibility to realize modifications for different applications. Therefore, many diamond tool manufacturers use production machines for the fully automatic fabrication of diamond segments with arranged diamonds. Because this novel approach is relatively new, the basic wear characteristics of such new developed tools have not been widely documented. For this reason, this paper focuses on the analyses of microcracks in the diamonds during the machining process in model segments with 4 diamond grains arranged in a square. The investigations were performed by computer tomography with an x-ray microscope.



51) Chemical pretreatment optimization for improved diamond adhesion on hard metal substrates

by S. Pratas1, E.L. Silva1, A.V. Girao1, C.M. Fernandes2, D. Figueiredo2, R.F. Silva1
1 CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, Aveiro, Portugal
2 Palbit S.A., Branca, Albergaria-a-Velha, Portugal

Abstract: A well-known way of improving the adhesion of diamond coatings on cemented carbide tools is chemical etching with Murakami and Piranha solution, prior to CVD deposition. However, several drawbacks can derive from it including tool fragilization and surface heterogeneity, which can compromise the performance of the tool. For this reason, the effectiveness of this type of wet chemical etching has been controversial. This study presents a contribution towards the development of this two-step chemical pre-treatment, by using WC-Co (7% wt.) substrates and addressing specifically the optimization of the step involving Murakami reagent, through the variation of its concentration and attack time. The main objective is to maximize the adhesion and homogeneity of diamond films grown by HFCVD on top of the pretreated substrates and to understand the chemical and microstructural effects leading to this optimization. Scanning Electron Microscopy (SEM), Raman spectroscopy and Optical Profilometry were used for the characterization, while coating adhesion was evaluated by Rockwell C indentation testing. The results show that the adhesion of the diamond coatings is dependent on the homogeneity of the substrate after WC etching. Furthermore, it was demonstrated that the optimization of the Murakami treatment can provide strong adhesion of multilayer diamond coatings.



News and Events

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60) Xiamen Stone Fair 2021. Rethink for a better future

62) Made expo chooses November

64) UCIMU: after the collapse of 2020, the Italian machine tool, robot and automation industry envisages a recovery already in 2021




Concrete Cutting

68) CSDA contractor assists in planning & engineering demolition of Arlington Memorial Bridge