Duration of the Project: 36 Months | Jan 2017
Partnership: AVIO SPA (Colleferro Plant) – SÒPHIA HIGH TECH (Sant’Anastasia Plant);
AMMEP [Additive Manufacturing by Mixing Elemental Powders] is a Research and Developed project co-funded by Italian Ministry of Economic Development Prog. n. F/050320/02/X32 – CUP: B38I17000430008 – COR: 309480.
Object: Manufacturing of the combustion chamber of the VEGA-E space launcher, through the Additive Layer Manufacturing process, using of advanced mixing technologies to obtain a custom metal powder.
The project focused on the construction of a specific subassembly of the thrust chamber (powered by liquid oxygen and both cryogenic liquid methane) of the third stage belong to the VEGA-E Launcher.
The thrust chamber consists of two main parts:
- the injection plate
- the combustion chamber
Project activities focued on the combustion chamber. This mechanical assembly allows the evolution of the combustion phenomenon and accelerates the combustion gases towards the nozzle. Furthermore, the combustion chamber cools the internal wall in contact with the gases to prevent the material from melting, as the combustion takes place at a temperature higher than 3000 [° K].
With the current materials on the market it is very difficult to obtain high performances. In general, the qualities of copper alloys, with a high heat transfer coefficient, are required to optimize the temperature exchange during the combustion phase. However these alloys are mechanically not adequate considering the stresses that are triggered during the process, moreover the material is not adequate to work at those temperatures. In addition, a nickel superalloy with superior mechanical properties compared to copper is exploiting and allows working at significantly higher temperatures.
Currently, the object in question is realized through a brazing process between copper liner and nickel alloy outer shell, or by a galvanic electroforming process of the nickel layer on the copper liner as shown in the figure below.
The production of the thrust chamber requires a very high number of working hours. Moreover, with the traditional production process, a discontinuous combination of the properties of the two materials is obtained, as can be seen from the following image.
The above-mentioned problem has been solved with the development of an advanced mixing technology of metal powders, such as to guarantee the homogenization of distinct metals (copper and nickel superalloy) in the particulate state. Then, by using ALM (Additive Layer Manufacturing) technology, we obtain the diffusion of the elements at the level of the crystalline grain which allow the formation of an MMC (Matrix Metal Composite) not present on the market. The main objective to be respected is to achieve a global thermal conductivity of the material major of 25 W/m°K.
Following it is possible to appreciate custom material (based on copper and nickel superalloy) specimen obtained by ALM
Then, the technological models representing Subscale prototypes of Vega E combustion chamber, produced during the project, have a continuous structure in which the single metal elements, homogeneously diffused in each other, enhance the characteristics of the object created. Furthermore, a reduction in the estimated time for production of more than 15% is expected and, above all, the manufacturing process is obtained in one single stage (decreasing the possibility of having component defects). Following It is possible appreciate Component Prototypes realized in the AMMEP Project, by using custom materials, obtained by metal mixing technolgy.