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The efficiency of hydroxyapatite depends on factors such as high sorption capacity, low water solubility, and high stability under reducing and oxidizing conditions [7].
Characterizations of HA: The HA samples were characterized for physic-chemical and microstructural properties using XRD, FTIR, SEM, and BET analysis [14-17].
Nguyen, Effect of Alkaline Activators to Engineering Properties of Geopolymer-Based Materials Synthesized from Red Mud, Key Engineering Materials 777 (2018) 508-512
Nguyen, Effects of Seawater Content in Alkaline Activators to Engineering Properties of Fly Ash-Based Geopolymer Concrete, Solid State Phenomena 296 (2019) 105-111
Pham, Engineering properties of lightweight geopolymer synthesized from coal bottom ash and rice husk ash, AIP Conference Proceedings 1954 (1) (2018) 040009

On the other hand, Si3N4 ceramic fibers and whiskers are used as reinforcing fibers in various matrices such as resins, metals and ceramics to improve the mechanical and thermal properties [1, 2].
Although the effects of heat treatment temperature and treatment time were investigated in these previous studies, few reports have studied the effects of additive elements contaminants during heat treatment and the nitrogen gas atmosphere conditions on the morphologies and properties of the obtained fibers.
The weight loss of sample ranged between approximately 20% and 30% for the tested nitrogen gas flow rates of 1-3 L∙min−1, suggesting that the nitrogen gas flow rate did not significantly affect the amount of sample production.
This excess amount of oxygen might be explained as follows in addition to the factor of EDS measurement error.
Kanzaki, Mechanical properties of silicon nitrides with tailored microstructure by seeding, J.

Introduction With the development of new materials and maching technologies, more and more structural ceramic parts are used to substitute for metal counterparts due to their excellent physical, chemical and mechanical properties [1] .
However, grinding effect and efficiency of ELID technology wasn't well-pleasing because of non-liner electrolysis action and multiformity or complicacy of influence factors.
In the grinding experiment, workpiece's material was hot press sillicon nitride and it's dimension is 20×20×12mm, preinstall peak voltage was 120V whose pulse width was 5μs and duty factor was 50%.
Correspondingly, contact stress between wheel and workpiece was slackened off, surface quality and machining effiency of workpiece would be affectted.
Analyzed cause for temporary decrease of space lies in that wheel's expand caused by heat is main factor after machine tool start no long time.

It might be cause the electrical property of floating gate.
After polysilicon chemical mechanical polish (CMP) process, the void was still observed nearby or at the floating gate surface, as shown in the figure 1 (b and c).
The profile before fill-in is an important key factor that affects the void existing or not.

Concrete structure due to the function of the internal factors and environmental factors, inevitably, appeared cracks[1], which are the reasons for the reduction, in the heat preservation performance concrete building structure, bearing capacity, the water proofing property and durability etc indicators.
However, the current research about super early strength grouting material is still not deep enough, early strength of grouting materials improvement often can bring the shrinkage of late strength, and people for shrinkage and long-term durability of the grouting material research is relatively lack, which seriously affect the popularization and application of super early strength grouting material[2] in practical engineering.
Mixing uniform ultra strength grouting material is made of 40mm*40mm*160mm blocks, which ,after Maintaining the regulation of hydration ages, are tested for the corresponding mechanical properties.
Table. 2 The properties of super early strength grouting material on different mix ratio High alumina  cement content {%} Final Setting time {min} Initial fluidity {mm} 30min fluidity { mm} 2h compressive {MPa} 1d flexural {MPa} 28d compressive {MPa} 90 compressive {MPa} 100 105 282 242 14.43 12.47 72.40 65.16 95 95 330 292 19.80 11.60 74.11 66.70 90 92 338 300 20.25 10.14 81.82 73.64 85 90 342 305 26.86 7.72 84.27 83.74 80 85 348 305 30.89 8.95 88.85 82.67 75 55 326 275 34.75 11.69 91.24 93.25 70 58 325 285 34.80 13.42 97.90 99.10 65 60 345 280 36.74 15.38 96.69 97.66 60 40 315 275 33.60 13.91 93.60 98.86 55 32 310 130 30.89 11.50 78.76 80.49 50 25 260 110 37.91 9.96 95.11 97.25 Results analysis Final setting time and fluidity.
Table. 3 The properties of super early strength grouting material on different glue sand ratio High alumina content Cement sand ratio Final Setting Time {min} Initial fluidity {mm} 2h compressive {MPa} 1d flexural {MPa} 28d compressive {MPa} 90d compressive {MPa} 65% 1.0 60 345 36.74 15.38 96.69 97.66 65% 1.2 60 350 28.40 11.82 88.2 93.21 65% 1.5 58 325 23.52 10.18 79.90 83.10 70% 1.0 58 325 34.80 13.42 97.9 99.10 70% 1.2 62 350 26.20 12.82 86.9 87.68 70% 1.5 55 348 22.92 10.74 78.60 84.66 As shown in Table 3, with the cement sand ratio increases, the initial flow, 30minflow, the flexural strength and compressive strength meet the requirements, but the compressive strength at different ages shows a decreasing trend, among which , 2h compressive strength decreases most.

Despite of the mentioned factors, the machining processes play significant role to produce components of smart materials, super alloys and other composites.
In these models, only shear strength of work material has been considered for calculation of cutting force as given in equations 1-3 and missing the factor affecting cutting process like strain at fracture and power for cutting.
Table 3 Chemical elements and Mechanical properties of EN-31 alloy Steel Chemical Contents Wt% C Si Mn Cr Co S P 0.9-1 0.10 0.30 1.2 0.025 0.040 0.04 Mechanical Properties Hardness (HB) Tensile strength (MPa) Elongation at breakage Shear strength (MPa) Strength coefficient K (GPa) Hardening exponent (n) Cohesive energy (Ech) J/m2 [2] 280 850 5% 520 1.34 0.25 4.2*104 The detail of input variables along with output responses have been mentioned in Table 2.
The chemical composition and mechanical properties of EN-31 has been listed in Table 3.
Mechanical Systems and Signal Processing 169 (2022): 108772

The obtained test results demonstrate that grinding wheels based on high-density polyethylene during finishing have their service factors at the same level or even higher than those of tools with other common types of binding substances [16, 17, 18].
The working peripheral surface of the experimental wheels after the very first pass acquired a dark shade (to a depth of about 0.1 mm) due to the thermal effect on polyethylene and some contamination by grinding products, which did not affect the stability of the tool properties in dynamics.
[Creation of instrumental diamond-containing materials on polyolefin matrices with a given set of properties.
[9] Vöth S., Korotkov A.N., Influence of Efficiency Factors of Gearing and Rope Drive in the Hoist Behaviour., E3S Web Conf.
Baboshkin, Tekhnologii shlifovaniya v mashinostroenii [Grinding technologies in mechanical engineering], St.

Keratin is widely used in leather chemical materials [5], functional materials [6] and biomedical materials [7] due to its special physical and mechanical properties.
Karthikeyan et al. [9] used sodium silicate to modify keratin to produce keratin-silica retanning agent, which enhanced the physical and mechanical properties of leather and imparted antibacterial properties.
The differences of properties were caused by the addition of chitosan.
Obviously, the modified keratin was a good auxiliary with high properties.
It was been found that the use of chitosan modified keratin in an appropriate amount for filling can also improve physical and mechanical properties.

Planar defects like stacking faults (SFs) and grain boundaries (GBs) are often present in such materials and may affect their properties.
The positron correlation potential and enhancement factor from [12] were taken considering the correction for incomplete positron screening.
They are slightly smaller than experimental ones [14] and result in about 4% lower unit cell volume, which also affects calculated positron characteristics.
In order to study the influence of yttrium on the GB properties, a Zr atom at the GB was substituted by Y at two different positions for each GB configuration studied.
From the quantum mechanical view point, both types of studied interfaces should represent twodimensional potential wells for positrons.

In order to increase the performance and thereby the effectiveness of different thermoelectric modules, especially advantageous thermoelectric properties of materials and also innovative design of thermoelectric devices are now solved.
Semiconductor alloys generally have good thermoelectric properties, i.e. relatively low electrical resistivity and also a low thermal conductivity, but their material efficiency is practically reduced due to an important structural element, namely a copper bridge connecting the semiconductor columns.
Although copper has a relatively high electrical conductivity and permits good soldering, the point is that after a relatively prolonged use, copper particles diffuse from the pure copper connecting bridge to the material of the columns and so degrade the initially excellent thermoelectric properties.
Summary For the demonstrated measurements, it is possible to predict specifically such optimum operational load for every thermal battery, with respect to its material and geometric properties, to be able to provide maximum performance, in particular linearly dependent on the temperature difference occurred between its walls.
One thing, however, is the heat allowed by theory (according to anticipated resistances and material properties of ternary alloys, the heating of the warmer wall up to 200 oC may be permitted), the second thing consists in the design of the thermal battery which is not able to withstand such long-term thermal load.