Anna Okunkova

Laser-beam modulation to improve efficiency of selecting laser melting for metal powders

Nowadays additive manufacturing becomes more and more popular. It depends on the results of last achievements in developing of the new constructions for modern machine tools. One of the most developed AM technology is SLM or SLS. About twenty years ago the technology of rapid prototyping started to grow up from building prototypes and developed to real functional item production. Especially this becomes more important in producing medical implants in the full accordance with individual digital 3D-model from metallic powder as Ti6Al4V or CoCr. The additive technology gives the possibility to reduce additional steps in implants production process as work preparation process, forwarding a work piece from one shop to another one, post treatment etc. This approach is very topical to production of tooth, knee and coxal implants. This idea is realized in the commercial SLM machines as EOS M280, SLM Solutions 125HL (Germany), Phenix systems PXS/PXM Dental (France) (fig. 1).

Manufacture of graphite electrodes for the electrospark machining of complex high-precision components

The manufacture of complex graphite electrodes for electrospark broaching is considered. Recommendations are made regarding the milling of graphite, and the design features of the electrodes are shown for a specific example.

Optical Monitoring and Diagnostics of SLM Processing for Single Track Formation from Co-Cr Alloy

The article presents a study of selective laser melting process (SLM) namely a study of stable track formation by the example of Co-Cr alloy. The characterization of the main process factors, which have an influence on the parts’ functionality, is developed. The experimental work for the research of two main factors as laser beam power and scanning speed showed the technological gaps for the formation of the stable tracks. The characterization of the non-stable single tracks’ defects is established. The new data about the main physical effects in the treatment zone is received by optical diagnostics of the process.

Mechanical Behavior of Alumina Toughened Zirconia Nanocomposites with Different Alumina Additions

ZrO2 and Al2O3 are monolithic ceramics used today in a wide variety of structural components. However, both materials present important drawbacks for some specific applications. In the case of Al2O3, its moderate strength (500 MPa) and toughness (4 MPa.√m) makes it unsuitable for high loading conditions. On the other hand, ZrO2 presents higher strength and toughness values (900 MPa and 6 MPa.√m) than Al2O3 but it is a material limited in its long-term behaviour due to its bad response to hydrothermal ageing and a pronounced tendency for subcritical crack growth. Due to this fact, ceramic nanocomposites made of Al2O3 and ZrO2 (ATZ and ZTA) have been developed in the last years in order to overcome the main drawbacks of the monolithic materials as they can combine the properties of both, strong and tough materials, simultaneously, with null ageing and even higher biocompatibility. In this work, several amounts of Al2O3 disperse phase (15, 35 and 50 vol %) were added to one ZrO2 matrix (CeO2 - 10 mol %) in order to see their effect on the mechanical properties, subcritical crack propagation and long-term reliability.