This research aims to study the effect of heat treatment on curing of reinforced Unsaturated Polyester Resin (UPR) with fiberglass, and to study the effect of storage time and the time of exposure to natural aging on curves absorption.
The results
showed that it is very difficult to reach a fully curing to UPR matrix, and
Storage samples for three years reveal resistance to degradation in fresh and seawater comparing with storage samples for three months, or aging by exposed to environmental for three years. The results showed also that the absorption occurs by thin film, and not prevent by increasing the layers of reinforcement
The aim of this work is to study the effect of the aging heat treatment on the pitting corrosion resistance of martensitic stainless steel. In this research a number of specimens from martensitic stainless steel were subjected to solution treatment a
t 1050 for one hour followed by water quenching then aging in the temperatures range (400-750) for different holding times (1-16 hrs).
After heat treatment, two types of corrosion tests (accelerated test and immersion test) were conducted. The results obtained in this research showed that the pitting corrosion resistance was
affected by Aging temperature and three critical temperatures were found in corrosion test: the
specimens aged at 475 0C had maximum corrosion rate. This may be due to the presence of stringer δ-
ferrite and precipitation of very fine precipitates which precipitated heterogeneously in the martensitic
matrix, which led to an increase in corrosion rate. The specimens aged at temperatures range (550 – 625) 0C had minimum values of corrosion rate, this is attributed to the high volume fraction of retained austenite. The specimens aged at temperatures above 625 had intermediate corrosion rate.
The type of pits, which resulted from two pitting corrosion tests, was independent form the form of δ-ferrite and carbides which presence in microstructure.
The influence of thermomechanical treatments on the microstructural properties of stainless steel D9 alloy
steel was studied.
There is considerable evidence supporting the role of gonadotrophins and
progesterone on follicular growth and maturation and functional maintenance
of the ovary in the hen. Recently, however, there are ever-expanding list of
factors may be involv
ed in establishing follicular growth and ovulation
currently including germinal disc region, growth factors, macrophages,
plasminogen activator, ornithine decarboxylase, inhibin, activin, follistatin,
relaxine, arginin vasotosin, oxytocin, prostaglandines, vasoactive intestinal
peptide, and their interactions.
This study deals with the most important problems related to the age of aging,
especially the social - psychological ones, which appear little by little as the age of man,
and from the increase in this segment on the one hand, and then seek to help
the elderly
and solve their problems on the other hand. This study deals with several aspects: First: the
concept of aging, its limits, its manifestations, second: the fertility that characterizes this
stage, the social problems of the elderly, the psychological problems of the elderly,
Problems of older persons. In conclusion, they made several proposals in order to
contribute to the goal of the study to focus attention on the elderly and to understand their
various problems in order to move towards solving them.
