Toz metalurjisi imalat yöntemi ile alüminyum matrisli TiC takviyeli kompozit malzeme üretimi ve çekme mukavemeti testlerinin analizi
Production of aluminum matrix TiC reinforced composite material by powder metallurgy manufacturing method and analysis of tensile strength tests
Yazar: HAKAN YILMAZ
Danışman: DOÇ. DR. AHMET ÇAĞATAY ÇİLİNGİR
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Makine Tasarım ve İmalat Bilim Dalı
Derece: Yüksek Lisans, 2024
Konu: Makine Mühendisliği = Mechanical Engineering

Özet:
Toz metalurjisi (T/M), günümüzde toz metaller, parçacık takviyeli kompozitler, 
seramikler, dövme işlemi, kalıplama gibi tekniklerin analizinden oluşan, metal 
tozlarının uygun standartlar ve belirli değerlerde karıştırılarak denetimli atmosfer 
şartlarında sinterlenmesiyle malzeme üretildiği bir imalat tekniğidir. Bu teknik
malzeme israfını minimize ederek, yüksek hassasiyet ve verimlilik sağlar. Bu 
yöntemde birbiri içinde çözünmeyen tozları uygun takviye malzemesi kullanılarak 
karıştırılıp soğuk presleme ve ardından sinterleme yapılarak istenilen özellikler 
sağlanılabilmektedir.
Bu çalışmada Al matrisli TiC takviyeli kompozit malzemeler, T/M imalat yöntemi 
kullanılarak üretilmiştir. Al7075 matris malzemesine ağırlık oranınca %0, %1, ve %5 
oranında TiC ve her karışıma %0,25 oranında sterik asit ilave edilerek toz karışımları
oluşturulmuştur. Elde edilen karışımlar 1, 2, 5 ve 10 saat boyunca mekanik alaşımlama 
test cihazında karıştırılmıştır. Elde edilen bu toz karışımları 450 Mpa basınçta soğuk 
presleme ile üretilip sinterleme fırınında 600 °C de 60 dakika boyunca sinterlenmiştir. 
Ardından roto fnish işlemiyle parçalar üzerindeki çapaklar temizlenmiştir. Üretilen 
numunelere deneyler yapılarak mikroyapıları ve çekme mukavemeti değerleri 
irdelenmiştir. Elde edilen numunelerde, hazne içerisindeki matris ve takviye malzeme 
tozlarının dağılımı, homojen olarak gözlemlenmiştir.
Deneyler sonucunda; ilave edilen TiC' e bağlı olarak kompozit malzemelerin ana 
bileşenlerinde farklılıklar gözlemlenmiş ve çekme mukavemeti değerlerinde 
etkilenmeler görülmüştür. Matris içindeki TiC oranı arttıkça parçacıkların daha fazla 
topaklanma olduğu görülmüş. Takviye elemanının (TiC) boyutunun nano boyutta 
olması, Al7075 matrisi oluşturan tozların makro boyutta olması neticesinde oluşan bu 
tane boyutu farklılığından dolayı, karışımda topaklanmalar oluşmuş ve bunun 
sonucunda porozite oranı artmıştır. Bunun ana sebebi, topaklanmalar sonucu Al7075
matris malzemesi ile TiC takviye malzemesi arasında yeteri kadar yüzey bağı 
sağlanamamış ve bu noktalarda poroziteler gözlemlenmiştir. Karışımı fazla 
karıştırmak tozların yapısını bozduğu kanısına varılmıştır.
TiC takviye malzemesi oranındaki artışla ve malzemenin nano boyutta olması 
sebebiyle çekme mukavemeti %1 karışımı için artmıştır. Hazırlanan kompozit 
malzemelere bakıldığında 2 saate kadar çekme mukavemeti değerlerinin arttığı
gözlemlenmiş, 2 saatten sonra bu değerler düşmeye başlamıştır. Bu demektir ki,
karışımı 2 saatten fazla karıştırmak tozların yapısını bozduğu gibi çekme mukavemeti 
değerlerini de düşürmüştür. Sonuç olarak; öğütülen kompozit malzemelerin çekme 
dayanımı test sonuçları irdelendiğinde en yüksek mukavemet değerinin %1 TiC 
takviyeli 2 saatlik karışım numunesinde olduğu belirlenmiştir.

Abstract:
Powder metallurgy (P/M) is a manufacturing technique that consists of the analysis of 
techniques such as powder metals, particle reinforced composites, ceramics, forging, 
and molding, and in which materials are produced by mixing metal powders with 
appropriate standards and specific values and sintering them under controlled 
atmospheric conditions. In other words, it is a method of producing parts by bringing 
metals into fine powder form, mixing them in a certain ratio, pressing them in precise 
molds at room temperature at pressures appropriate to predetermined technical values, 
and then sintering them under controlled atmospheric conditions. 
This method consists of various stages such as powder production, blending the 
obtained powders, compacting the powders, sintering and optional additional 
processes (infiltration, oil impregnation, deburring, etc.).
This technique minimizes material waste and provides high precision and efficiency. 
In this method, powders that do not dissolve in each other are mixed using appropriate 
reinforcement materials, cold pressing and then sintering are performed to obtain the
desired properties.
Composite materials constitute a category of advanced technological materials. These 
materials are the first materials developed by humanity to protect itself from external 
factors and have begun to enter almost every area of our lives in this century, and their 
areas of use are also rapidly expanding. 
Parts produced with the P/M manufacturing method have many areas of use in the 
sector. These include various applications such as aircraft brake pads, high-power 
lights, electrical contact elements, bearings, armor-piercing bullets, automobile 
transmission shafts, orthopedic prostheses, nuclear fuel rods, rechargeable batteries, 
high-temperature filters, electronic capacitors, watch cases and jet engine turbines. In 
addition, this production method has many advantages such as low investment costs, 
flexibility of the equipment used, high efficiency and easy production of materials with 
different properties.
The mechanical alloying technique is a powder processing method used to improve 
solid state reactions and material properties. This method is usually carried out by 
grinding micron-sized metal powders in a high-energy mill. The mechanical alloying 
technique is used to mix a series of materials homogeneously and to form new, usually 
amorphous or nanocrystalline materials.
During the mechanical alloying process, the sufficient force applied to the powders 
grinds the powders and bonds are formed between the formed powder particles at low 
temperature. The internal structure of the final powder is usually finer than the powders
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formed by atomization. The microstructure has particles of similar size formed by 
serial cooling methods. In addition, the powder particles are positioned between the 
balls. This causes elongation in the microstructure and increases the mechanical 
quality.
Technically, the mechanical alloying method is generally a suitable technique for the 
production of metal matrix composite materials. The reason is that it allows to obtain 
specialty at a high level from the qualities handled with other techniques. This method 
is to ensure that the reinforcement material is spread homogeneously within the matrix 
by removing the agglomeration of the reinforcement particles. Furthermore, if there is 
a fault in the reinforcement material as a result of this continuous impact, it eliminates 
it and prevents the composite material from deforming suddenly. With the use of this 
method and these powders, not only the unprocessed states but also the problems that 
arise with different techniques are eliminated.
Recently, aluminum matrix composites have been used in the automotive industry, 
especially in applications such as engine pistons, cylinder liners, brake discs and 
drums, thanks to their low cost, lightness, high strength, high elasticity modules and 
superior wear resistance.
Ceramics, especially silicon, which is frequently encountered in the kitchen, and 
kardur, the favorite of chefs, are used to strengthen the mechanical properties of 
aluminum matrix composites.
The main reinforcement materials used to strengthen the mechanical properties of 
aluminum matrix composite materials are ceramics such as TiC, SiC, B4C and Al2O3. 
Since our country has rich boron resources, B4C composite material stands out with 
its superior physical and chemical properties.
Composite materials are increasingly attracting the attention of researchers due to their 
low cost, lightness, superior mechanical and thermal properties. Composite materials 
are classified as metal, ceramic and polymer matrix composites depending on the 
matrix material. Metal matrix composite materials consist of a matrix material 
consisting of reinforcement elements in particle form and a metal or alloy. Metals such 
as aluminum (Al), titanium (Ti), magnesium (Mg), copper (Cu) are generally preferred 
as matrix materials, and metal nitrides (Si3 N4 , TiN, TaN, ZrN etc.), metal carbides 
(SiC, B4 C, WC etc.) and metal oxides (Al2 O3 , SiO2 , ZrO2 etc.) are preferred as 
reinforcement elements.
Aluminum is often preferred as the matrix material in MMK materials because it has 
an almost 100% recycling rate, is easily formed, is lightweight, and has good electrical 
and thermal conductivity. It is used extensively due to these properties. Nowadays, 
aluminum and its alloys are used in a number of sectors such as construction, aviation, 
aerospace and the automotive industry.
In this study, Al matrix TiC reinforced composite materials were produced using the 
P/M manufacturing method. Powder mixtures were created by adding 0%, 1% and 5% 
TiC by weight to the Al7075 matrix material and 0.25% steric acid to each mixture. 
The resulting mixtures were mixed in a mechanical alloying test device for 1, 2, 5 and 
10 hours. The obtained powder mixtures were produced by cold pressing at 450 Mpa 
pressure and sintered in a sintering furnace at 600 °C for 60 minutes. Then, the burrs 
on the parts were cleaned with roto finish process. Experiments were performed on the 
produced samples and their microstructures and tensile strength values were examined. 
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In the obtained samples, the distribution of matrix and reinforcement material powders 
in the chamber was observed homogeneously. 
As a result of the experiments; differences were observed in the main components of 
the composite materials depending on the added TiC and effects were observed in the 
tensile strength values. It was observed that the particles were more agglomerated as 
the TiC ratio in the matrix increased. Due to this grain size difference that occurred as 
a result of the reinforcement element (TiC) being in nano size and the powders forming 
the Al7075 matrix being in macro size, agglomerates were formed in the mixture and 
as a result, the porosity rate increased. The main reason for this was that sufficient 
surface bonding could not be provided between the Al7075 matrix material and the 
TiC reinforcement material as a result of agglomerations and porosities were observed 
at these points. It was concluded that mixing the mixture too much disrupted the 
structure of the powders. With the increase in the TiC reinforcement material ratio and 
due to the nano-sized nature of the material, the tensile strength increased for the 1%
mixture. When the prepared composite materials were examined, it was observed that 
the tensile strength values increased up to 2 hours, and these values began to decrease 
after 2 hours. This means that mixing the mixture for more than 2 hours disrupted the 
structure of the powders and also reduced the tensile strength values. As a result; when 
the tensile strength test results of the milled composite materials were examined, it was 
determined that the highest strength value was in the 2-hour mixture sample with 1% 
TiC reinforcement.