The chosen, typical causes of quality defects of cast-iron „alphin” rings embedded in aluminum cast are being presented in this paper.

Diffusive joint of those inserts with the pistons casts is being used, due to extreme work conditions of destructive influence of the fuel mix

and variable thermo-mechanical loads, which reign in the combustion motor working chamber.

In the dissertation it has been shown, that so called „time-thermal treatment” (TTT) of the alloy in liquid state, as overheating the metal

with around 250o

C above the Tliq. and detaining it in this temperature for around 30 minutes, improves the mechanical properties (HB, Rm,

R0,2). It was ascertained, that overheating the AlSi17Cu5Mg alloy aids the modification, resulting with microcrystalline structure. Uniform

arrangement of the Si primeval crystals in the warp, and α(Al) solution type, supersaturated with alloying elements present in the base

content (Cu, Mg) assures not only increased durability in the ambient temperature, but also at elevated temperature (250o

C), what is an

advantage, especially due to the use in car industry.

In the dissertation it has been shown, that so called “time-thermal treatment” (TTT) of the alloy in liquid state as overheating the metal

with around 250o

C above Tliq. and detailing it in temperature for 30 to 40 minutes has the influence on changing the crystallization

parameters (Tliq., TEmin.

, TEmax., TE(Me), TSol.). It was ascertained, that overheating the AlSi17Cu5Mg alloy substantially above Tliq. results

with microcrystalline structure. Evenly distributed in the eutectic warp primeval silicon crystals and supersaturated with alloying additives

of base content (Cu, Mg, Fe) of α(Al) solution, ensures not only increase durability in ambient temperature, but also at elevated

temperature (250o

C), what due to it’s use in car industry is an advantage.

The FMEA (Failure Mode and Effects Analysis) method consists in analysis of failure modes and evaluation of their effects based on

determination of cause-effect relationships for formation of possible product or process defects. Identified irregularities which occur

during the production process of piston castings for internal combustion engines were ordered according to their failure rates, and using

Pareto-Lorenz analysis, their per cent and cumulated shares were determined. The assessments of risk of defects occurrence and their

causes were carried out in ten-point scale of integers, while taking three following criteria into account: significance of effects of the defect

occurrence (LPZ), defect occurrence probability (LPW) and detectability of the defect found (LPO). A product of these quantities

constituted the risk score index connected with a failure occurrence (a so-called “priority number,” LPR). Based on the observations of the

piston casting process and on the knowledge of production supervisors, a set of corrective actions was developed and the FMEA was

carried out again. It was shown that the proposed improvements reduce the risk of occurrence of process failures significantly, translating

into a decrease in defects and irregularities during the production of piston castings for internal combustion engines.

In this paper we present the current status of modelling the time evolution of the transient conductivity of photoexcited semi-insulating (SI) 4H–SiC taking into account the properties of defect centres. A comprehensive model that includes the presence of six, the most significant, point defects occurring in SI 4H–SiC crystals is presented. The defect centres are attributed to the two kinds of nitrogen-related shallow donors, a boron-related shallow acceptor, deep electron and hole traps, and the Z_1/2 recombination centre. We present the results of the state-of-the-art numerical simulations showing how the photoconductivity transients change in time and how these changes are affected by the properties of defect centres. The properties of defect centres assumed for modelling are compared with the results of experimental studies of deep-level defects in high purity (HP) SI 4H–SiC wafers performed by the high-resolution photoinduced transient spectroscopy (HRPITS). The simulated photoconductivity transients are also compared with the experimental photocurrent transients for the HP SI 4H–SiC wafers with different deep-level defects. It is shown that a high-temperature annealing producing the C-rich material enables the fast photocurrent transients to be achieved. The presented analysis can be useful for technology of SI 4H–SiC high-power photoconductive switches with suitable characteristics.