Joinability of Centrifugal Composite Castings

Centrifugal composite castings based on aluminium alloys belong to a group of materials with high potential for application in the automotive and aerospace industries. Their use is limited by the lack of a technology enabling the obtainment of a permanent joint ensuring safe operation. The article presents the results of preliminary surfacing and welding tests of a hybrid centrifugal composite casting based on the AlSi12 alloy and reinforced with silicon carbide (5 % by weight) and glassy carbon (5 % by weight) particles. Structural tests and the quantitative evaluation of the distribution of structural constituents indicated the possibility of the joining of such composites using the TIG welding process. It was found that overlay welds made using the filler metal having a chemical composition similar to that of the matrix could be treated as a buffer layer. The aforesaid approach should enable the joining of composite castings. The structure of the weld revealed the presence of heterogeneously distributed reinforcing phases, which was related to the gradient structure of centrifugal composite castings. The presence of the Al4C3 phase at the interface between the glassy carbon and the matrix could result in the reduction of corrosion resistance in a humid environment. The structural tests discussed in the article should be supplemented with the assessment of the mechanical properties of the joint. As a result, it will be possible to implement the technology for the welding of composite castings on an industrial scale.

Improvement of the properties of the surface layer of cast iron castings

The possibility of improving the mechanical properties and corrosion resistance of the casting surfaces is being considered. The impregnation of the powder composition with liquid iron when it is poured into a casting mold to obtain surface-alloyed castings with a low content of chromium and nickel is proposed. Keywords: surface alloying, powder composite, casting, casting mold, pasting. [email protected]

COMPOSITE CASTINGS WITH DIFFUSION BONDS BETWEEN ELEMENTS

The article is devoted to the current problem of improving foundry competitiveness. With a continuous increase in load, speed, power, temperature, the influence of aggressive environments, and other factors, an adequate increase in the requirements for the operational properties of parts is observed. Composite casting allows us to obtain high-precision castings following all the requirements that apply to them. Composite casting synthesizes individual elements of a part, which can be performed by the most efficient farming methods for a given element, as well as from optimal materials, depending on the requirements for the parts. The main content of the study is the analysis and detailing of the parameters of an economical technology to produce high-precision composite castings with differentiated physical and mechanical properties of their parts and high operational reliability. Considerable attention is paid to contact processes that communicate between elements. In most cases, these are diffusion interactions determined by defects in the crystalline structure. The contact zone should be homogeneous and controllable in geometric parameters and properties in areas where complex physicochemical processes occur under unsteady thermal conditions. The characteristic features of the production of composite castings are highlighted and described, taking into account the choice of elements for each specific case, with the determination of the parameters that determine the relationship between them on specific examples of the preparation of composite castings. The results of the study confirmed stable performance, reduced costs for the manufacture of castings, metal savings (for example, up to 2 kg per cone). The results indicate a high potential of composite casting as a means of increasing the competitiveness of foundry by manufacturing high-precision castings with an increased operational reliability of cast parts.

Structure and Properties of Heterocomposite Polymeric Materials and Coatings from them Obtained by Heliotechnological Method

The paper presents the results of the study of the creation of new hetero-composite casting polymer materials and coatings from them. The effect of ambient temperature on microhardness and impact strength of polymer coatings is studied. It has been found that treatment of the polymer composition with solar radiation is an effective way of controlling the curing reaction, saving energy in the preparation of high viscosity epoxy compositions, which is important for their practical implementation in the industry for process equipment and products operating under conditions of corrosive hydroabrasive wear.