Addition Of Aluminum Nitride Research Articles

Effect of Aluminum Nitride Addition on Dry Wear Properties of Al-11%Si Alloy Prepared by Stir Casting Process

Dry wear properties of aluminum nitride (AlN) reinforced aluminum-11% silicon alloy (Al-11%Si) was studied using a pin-on-disc configuration wear tester. Different weight percentages of AlN (0 – 10 wt.%) powder were added to the Al-Si alloy, melt and stir cast via bottom pour technique to form composites of Al-Si alloy/AlN. The dry sliding wear test were performed at a room temperature (27°C), under 25N and 70N load with fixed velocity of 1ms-1 and sliding distance between 1 to 5 km. The addition of 10 wt% of AlN improved wear resistance of Al-Si alloy by 72% and 130% indicated by volume loss for 25N and 70N load respectively. Mixed-wear mechanism of delamination, adhesion and abrasion was observed for the composite when applied loads were 25N and 70N while delaminating mechanism was dominance for Al-Si matrix alloy. Both Al-Si alloy with and without AlN reinforced found with FE element from counter-face disk that shows material transfer was significant.

Effect of Aluminum Nitride (AlN) Addition on Wear and Mechanical Properties of Al-Si Alloy Composites Fabricated by Stir Casting Process

The effect of AlN addition in Al-Si alloy composites on the mechanical properties and dry wear behaviour were studied using pre-selected parameter conditions. In this work, high purity of AlN powders with different weight percentage of 5, 7 and 10 were used as reinforced materials for the composites. Morphology of the reinforced composite indicated that both silicon grains and inter-metallic compounds were surrounded by the AlN particles. The presence of AlN in the Al-Si alloy showed a significant improvement in tensile properties in which 7wt% of AlN addition increased up to 25% compared to those of without any reinforcements. Fracture morphologies with small dimples, tear ridges and necking features indicated that ductile fractures had occurred on the Al-Si composites. At 25N load, alloys with 5wt% of AlN exhibited high wear resistances whereas at 70N, alloys with 10wt% of AlN showed a great improvement in wear resistance. SEM investigation also revealed that the presence of wear was also marked with prominent grooves, craters and scoring marks. Overall, alloys with 7wt% AlN addition possessed great improvement in hardness, tensile and wear resistance properties.

The Preparation and Cure Kinetics Researches of Thermal Conductivity Epoxy/AlN Composites

The aluminum nitride (AlN) was employed to prepare epoxy/AlN composites by blending-casting moulding method, two different coupling agents were used to functionalize the surface of AlN. The thermal conductivity and mechanical properties of the composites were investigated. And the cure kinetics of the EP/AlN composites was studied by means of isothermal DSC. Results revealed that the thermal conductivity of EP improved remarkably with the addition of AlN, a higher thermal conductivity of 1.05 W/mK can be achieved with 42 vol% AlN, about 5 times higher than that of native epoxy resin. And the flexural and impact strength of the EP/AlN composites were optimal with 3.3 vol% AlN. The curing process of the EP/AlN composites contained autocatalytic mechanism, the whole process was according with the Kamal model. The presence of AlN did not change the cure reaction mechanism, and had little effecting on the activation energy, but decreased the rate constants kl and k2.

Dynamic mechanical properties of aluminum nitride/cyanate ester composites for high performance electronic packaging

AbstractViscoelastic ature is one of the key features of polymeric composites. A series of cyanate ester (CE)‐based composites with different aluminum nitride (AlN) contents for high performance electronic packaging, coded as AlN/CE, were developed; the viscoelastic nature of AlN/CE composites was intensively investigated by employing dynamic mechanical analysis (DMA). Results show that the AlN content has a great effect on dynamic mechanical properties of AlN/CE composites. The storage modulus in the glassy region increases linearly with the addition of AlN as well as the increase of AlN content. Meanwhile, all composites also exhibit notably higher loss modulus than cured CE resin due to the appearance of new energy dissipation forms. In addition, the incorporation of AlN has a significant effect on damping factor peak. All reasons leading to these phenomena are analyzed from the view of structure–property relationship. Copyright © 2009 John Wiley & Sons, Ltd.

Thermal conductivity and mechanical properties of aluminum nitride filled linear low‐density polyethylene composites

AbstractTo acquire polymer composites with high thermal conductivity and mechanical properties, the aluminum nitride (AlN) microparticles modified with titanate coupling reagent of isopropyltrioleictitanate (NDZ‐105) were employed to blend linear low‐density polyethylene (LLDPE) via powder mixing method. Thermal conductive coefficient of the AlN/LLDPE composites was measured using hot disk thermal analyzer, and the thermal stability characteristics of AlN/LLDPE composites were mainly investigated via thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC). The results indicated that the use of AlN particles modified by NDZ‐105 significantly enhanced thermal conductivity and mechanical properties of AlN/LLDPE composites. The thermal conductivity coefficient λ was 1.0842 W/mk with 30% volume fraction of AlN, about three times higher than that of native LLDPE. The tensile strength of composites was maximum (17.42 MPa) with 20% mass fraction of AlN. DSC analyses results indicated that AlN had an influence on the melting temperature and the crystallinity of LLDPE. Additionally, TGA analyses showed that the thermal stability of LLDPE was significantly increased with addition of AlN. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Preparation and Thermal Ablation Behavior of HfB2–SiC‐Based Ultra‐High‐Temperature Ceramics Under Severe Heat Conditions

HfB2–SiC‐based ultra‐high‐temperature ceramics with aluminum nitride (AlN) as a sintering aid were hot pressed at 1850°C. The sinterability and mechanical properties were investigated and compared with the composite without a sintering aid. It was shown that the addition of AlN greatly improved the powder sinterability and enabled the production of a nearly full‐dense composite. The mechanical properties, especially the flexural strength, were enhanced remarkably through the improvement in the sinterability and microstructure. The oxidation resistance of a composite doped with 10 vol% AlN was evaluated by a plasma arc heater and the ablation mechanism was discussed.

Effect of AlN as sintering aid on hot-pressed ZrB 2–SiC ceramic composite

ZrB 2–SiC ceramic composites were prepared from commercially available powders by hot-pressing, and aluminum nitride (AlN) was added as a sintering aid. Sinterability, microstructure and mechanical properties were investigated and compared to the composite without AlN. It was shown that the addition of AlN greatly improved the powder sinterability and enabled the production of nearly full dense composite. The flexure strength, hardness and fracture toughness were improved with a small amount (5 vol.%) of AlN due to the improvement in densification and inhibition of grain growth. Meanwhile the sinterability and mechanical properties were greatly enhanced with the introduction of finer starting powders. However, the flexural strength and fracture toughness were not improved much when more AlN was added.

Improvement of piezoresistance properties of silicon carbide ceramics through co-doping of aluminum nitride and nitrogen

The piezoresistance coefficient was measured on co-doped silicon carbide ceramics. Evaluation samples of α-silicon carbide ceramics were first fabricated by glass capsule HIP method using powder mixture of silicon carbide and aluminum nitride with various ratios. The resultant aluminum nitride added silicon carbide ceramics were doped with nitrogen by changing the post-HIP nitrogen gas pressure. The lattice parameter increased with the amount of adding aluminum nitride indicating that the incorporated aluminum substituted smaller silicon atoms. After post-HIP treatment, lattice parameter then decreased with nitrogen gas pressure. The piezoresistive coefficient increased with the addition of aluminum nitride, it further increased with the nitrogen doping pressure.