35 research outputs found
Management of Brazilian hardwood species (Jatoba and Garapa) wood waste biomass utilization for energy production purposes
ArticleIn the
Federative
Republic of Brazil,
Jatoba (
Hymenaea courbaril
) and Garapa
(
Apuleia
leiocarpa
) trees
are intensively harvested
. The yield of one log is approximately
45
–
55%, which
indicates a
great
amount of produced wood waste biomass.Present research
monitored the suitability of wood waste biomass from Jatoba and Garapa trees for bio
–
briquette
for solid biofuel production.
The research
was focused on chemical parameters,
and
energ
y
potential of such biomass kinds. Jatoba wood waste biomass was used for the
production
of bio
–
briquette fuel and its final mechanical quality was investigated by determination of their
mechanical quality indicators.
Results of chemical analysis (in wet b
asis) exhibited
great
level of
ash content in case of both species (
Jatoba
–
0.31%, Garapa
–
3.02%), as well as high level of
energy potential; net calorific value
equal to 18.92
MJ
kg
–
1
for Jatoba and to
18.39
5
MJ
kg
–
1
for
Garapa. Analysis of elementary
composition proved following levels of oxygen content: J
atoba
–
41.10%, Garapa
–
39.97
%. Mechanical analysis proved bio
–
briquette samples volume
density
ρ equal to
896.34
kg
m
–
3
which indicated quality
bio
–
briquette fuel
, while the
level
of rupture
force R
F occurred at a
lower
level
–
47.05
N
mm
–
1
. Most important quality indicator, the
mechanical durability DU,
unfortunately,
occurred at a
lower
level; DU
=
77.6% compared to the
minimal level of bio
–
briquette fuels intended for commercial sales which must
be >
90%. Overall
analysis proved materials suitability for energy generation purpose with certain limitations which
can improve by changing production parameters of
briquetting
Fracture toughness in some hetero-modulus composite carbides: carbon inclusions and voids. Advances in Applied Ceramics
Fracture toughness of ceramics in some cases can be significantly improved by the inclusion of low-modulus phase and even voids. Structure and mechanical characteristics of dense ceramic composites synthesised by reactive hot pressing of TiC-B4C powder mixtures at 1800 - 1950°С under 30MPa during 16 minutes are investigated. X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM and EDX) have shown that during hot pressing solid phase chemical interaction 2TiС + B4C = 2TiВ2 + 3С has occurred resulting in TiB2-TiC-C, TiB2-C or TiB2-B4C-C hetero-modulus composite formation with approximately 1μm carbon precipitates. The volume of such precipitated carbon can reach 35 vol. %. The fracture toughness depends on the precipitate size and amount of graphite precipitation and has a distinct maximum K1C = 10MPa∙m1/2 at nearly 7 vol. % . Such fracture toughness behaviour is explained by the proposed model of crack propagation and the model-based assessment of hetero-modulus ceramic fracture toughness. It is shown that voids and low modulus carbon inclusions blunt the cracks and can increase ceramic toughness. The later has been demonstrated in the another carbon containing ceramic Cr2AlC, so named MAX phase material, when thin film fracture resistance increases as the ceramic was deposited to be porous
Materials Problems of Plasma Guns Designated for Decomposition of Toxic and Persistent Compounds
Preparation and Properties of Spheroised Tungsten Powder
In our series of experiments ball shaped tungsten particles were prepared.Tungsten microballs can be used in filters for chemical and metallurgical industry.Possible applications can be awaited in nuclear fusion reactors.Tungsten balls are tested also as special type of ammunition.Coarse tungsten powder of OSRAM Sylvania Inc provenience was screened into fractions 40-60ćm, 60-100ćm
Chemical aspects of the anti-ballistic armors preparation by plasma deposition
This paper informs about possibility to deposit ceramic-metallic composites on different types of metallic and ceramic substrates by thermal spraying, namely plasma spraying. Preparation of free-standing deposits as well as metal-reinforced composites is described. Results of plasma deposition of two ultra-hard ceramic materials (titanium boride and nitride) are presented in more details. Plasma deposition of materials carried out in specific technological conditions preventing undesirable high-temperature oxidation of ultra-hard ceramics is costly. Therefore, deposition conditions which should lead to improvement of surface properties of currently used antiballistic ceramics were studied and described
Diffusion of steel oxidation produts through plasma sprayed protective ceramic coatings into glass melt
Study of the Phase Transfer in Titanium-Skandium Alloys
The contribution describes the attempt to use the dilatometric method for determination of phase transformation in titanium alloys with 5wt% and 15wt% of scandium.Arc melting Ti-Sc alloys, rolling of obtained ingots and their adjustment to test probes.The dilatometric measurements proceeded to temperature 1200Cbecause even most pure accessible argon atmosphere did not prevent from
Processes of Nanoparticle Formation in Low Temperature Plasma
This work describes the synthesis of nanoparticles during interaction of several different metals (Ag) or their respective oxides (TiO2, Cr2O3) with oxygen-hydrogen plasma having temperatures above 25000 K. Resulting nanoparticles and/or their aggregates in the size range of 25-300 nm were deposited on metallic targets and/or trapped in the water filters and separated using ultra-centrifugal apparatus. The aerosol spectrometer SMPS 3936 (scanning mobility particle sizer) was used to study the particle size distribution of generated nanoparticles in the size range 14 – 700 nm. In order to extend the measured particle size range towards larger sizes, the APS 3321 spectrometer (aerodynamic particle sizer) with the size range 500-20000 nm was used simultaneously. Both spectrometers were set-up to sample with three minute time resolution. Process conditions and production of inorganic nanoparticles of defined composition are discussed in this work