Effect of isothermal heat treatment on hardness of X7475 aluminium alloys

The heterogeneous nature of microstructure in most as-cast alloys has created the unique properties for an ally before heat treatments. The scanty nature of scholarly articles on the effect of heat treatments on the hardness of new alloys produced from recycled aluminium alloys prompts this investigation. In this work, we upgraded from 3 series to 7 series alloys to form a new material. Previous attempts were also silent on the Alcao Green Letter specifications of the 7 series alloys, hence producing a 7475 alloy that may not be within the Alcao specifications. This paper presents the result of preliminary studies on new experimental X7475 Al-alloy that was produced per Alcoa Green Letter specifications, with variations of Zn (4.0 - 5.0 wt.%), Mg (1.00 - 1.50 wt.%) and Mn (0.025 - 0.075 wt.%), then subjected to microhardness probe under a load of 490.3mN (0.05Hv) and 10sec duration after isothermal and isochronous “O”, T4 and T6 heat treatments. Heating and cooling rates were controlled during heat treatment processes to investigate the effects on the formation of the MgZn2 and other precipitates on the mechanical properties of the alloy. Peak obtainable hardness value of 140.45 Hv and 134.32 Hv are attained within the T6 and T4 conditions in an alloy of 4% and 5% Zn respectively. The increase in wt.% of Zn favours mechanical properties while reverse is the case for Manganese. This result is an indication of the load bearing capacity of our alloy. It has also demonstrated the success in upgrading the 3 series to 7 series alloys from secondary materials. However, the result could be improved on after composition, heat treatments and production route optimization

Optimization of wear and hardness of Al–Zn–Mg–Cu alloy fabricated from recycled beverage can using response surface methodology

A novel X7475 (Al–Zn–Mg–Cu) alloy was fabricated from recycled beverage cans (RBCs). Al was recovered from RBC. Zn and Mn were sourced from spent batteries, while Cu was sourced from copper wire. The weight percent (wt%) Zn was varied at 4, 4.5 and 5. Following the fabrication of rods, samples were taken through precipitation and artificial ageing at 475 °C and 145 °C respectively. The pin-on disc method within ASTM G99-17 was used for the wear test, while hardness post-mortem was done using ASTM E18 specifications. Wear mass loss (WML) and hardness were optimized using response surface methodology (RSM). The least WML of 0.017 g and maximum hardness of 142 HV were obtained from an alloy fabricated using 5 wt% Zn, when subjected to a load (L) of 30 N, speed (S) of 400 RPM and time (T) of 10 min. The MWL of 0.011 g and least hardness of 71 HV were observed in an alloy of 4 wt% Zn under a load of 20 N, with S, and T at 150 RPM and 6 min apiece. Formation of hardening precipitates like Al2CuMg, MgZn2 and CuAl2, were suggested to be responsible for the low WML and hardness observed in the alloys. The result confirmed the significant of the optimization model at a confident interval of 95% ( R2 = 0.9531). Additional experiment was suggested for correlating hardness with tensile strength

Comparison of carcass and meat quality in goats subjected to preslaughter head-only electrical stunning or slaughtered without stunning

The effects of slaughter without stunning in comparison with head-only electrical stunning (HOES) on carcass hemorrhages and meat quality in goats were evaluated. Sixteen Boer crossbred bucks were subjected to either non-stun (NS) or HOES (1 A, for 3 s at 50 Hz). Meat quality traits such as pH, water holding capacity (WHC), color, tenderness, myofibril fragmentation index (MFI) and sarcomere length were assessed on semitendinosus (ST) muscle, while the incidences of hemorrhage were morphologically examined on shoulders and legs of each carcass. The results indicate no differences (p > 0.05) in meat quality traits between NS and HOES goats. However, carcasses obtained from the head-only electrically stunned goats had higher (p < 0.05) incidence of hemorrhages than those slaughtered without stunning. HOES prior slaughter increased carcass hemorrhages without adversely affecting meat quality traits in goats

Effects of dietary oil blend on fatty acid composition, oxidative stability and physicochemical properties of Longissimus thoracis et lumborum muscle in goats

This study examined the effects of dietary blend of 80% canola oil and 20% palm oil (BCPO) on the physicochemical properties, antioxidant status, oxidative stability and fatty acid composition of Longissimus thoracis et lumborum (LTL) muscle from goats during chill storage. Over a 14-week feeding trial, 24 Boer bucks were randomly assigned to and supplemented with diets containing 0, 4 or 8% BCPO on a dry matter basis, slaughtered and the LTL was subjected to a 7 day chill storage. Neither diet nor post mortem ageing influenced (P > 0.05) antioxidant enzyme activities, chemical composition and cholesterol. Diet had no effect on the carbonyl content, free thiol content, water-holding capacity, tenderness, pH and glycogen. Oil-supplemented goats had higher (P 0.05) changes were found in the proportion of individual fatty acids throughout storage. Total polyunsaturated fatty acids (PUFA) decreased while total saturated fatty acids increased as storage progressed. Dietary BCPO enhanced n-3 PUFA without compromising the quality attributes of chevon

Effect of imperfections on and modelling of conductivity and hardness of high-Zn X7xxx cast al-alloys produced from recycled beverage can

In this paper, the effect of imperfections as a result of formation of new phases on electrical and macro hardness property of a novel experimental high-Zn Al-Zn-Mg-Cu alloys produced from recycled beverage can was investigated with the aim of correlating hardness with conductivity using ANOVA. Alloys were observed in the As Cast (AC), annealed (O), natural aged (T4) and artificial aged (T6) conditions. Heat treatments supported the formation of hardening precipitates like the Al2.06Fe4, α-AlFeSi, Al7Cu2Fe, θ(Al2Cu), β-AlFeSi and MgZn2 phases. Imperfections inform of voids and contaminants are by-products of recycled aluminium and casting route. Peak obtainable hardness of 122.94 HV in the T6 condition was observed in an alloy of Al-5.0 Zn-1.5 Mg- 0.35 Cu. The same alloy’s conductivity is 3.676 107 S/m. The least hardness of 38.16 HV and conductivity of 3.533 107 S/m is credited to an alloy of Al- 5.0 Zn-1.00 Mg-0.35 Cu in the O condition. The relationship between hardness and conductivity is nonlinear. Models developed to predict the hardness of this experimental alloys fits all the variables and covers the AC, O, T4 and T6 respectively. The need for further investigation on the imperfections, optimization of mechanical properties and additional mechanical properties investigation is required

Effect of Annealing and Artificial Ageing Parameters on The Ultimate Tensile Strength and Elongation of New Al-(4-5) Zn- Mg-Mn-Cu Alloys Fabricated using Recycled Beverage Cans

The transport industry is one of the highest consumers of aluminium alloys. However, the quest for new and cheaper aluminium with properties comparable to the contenders has remain in the research domain for sometimes. Even at that, the literature is dearth of clear ideas on conversion of the huge RBCs to X7475 experimental alloys. In furtherance to the fabrication of a new 7xxx (Al-4-5Zn-1.5Mg-1.0Mn-0.35Cu) alloy from Recycled Beverage Cans (RBCs), the effect of annealing temperature (350 oC, 380 oC and 413 oC) and artificial ageing time (6, 10.5 and 15 hours) on the ultimate tensile strength (UTS) and elongation (e) were reported. Nine samples (S1-S9) of experimental alloys were fabricated and subjected to tensile tests, SEM/EDX and XRD analysis. Secondary phases like MgZn2, Cu2Mg precipitates as observed in the XRD supported an improved UTS. The elemental analysis revealed the presence of alloying compositions. An alloy fabricated using Al-5Zn-1.5Mg-1.0Mn-0.35Cu (S9), artificially aged at 6 h and annealed at 413 oC had the highest UTS of 362.2 MPa and an elongation of 3.09 mm (15.45 %). The result demonstrated that a new X7475 alloy was fabricated from RBCs with comparable mechanical properties with alloys fabricated using pure aluminium.&nbsp;&nbsp;&nbsp

Relating fractographic analysis to yield strength of novel X7475 (Al–Zn–Mg–Cu) alloys produced by recycling aluminium beverage cans

The aim of this letter was to conduct a postmortem on the nature of fracture, substrates and possible precipitates formed in a novel experimental 7xxx alloy cast from recycled beverage cans (RBCs) and link same to yield strength (ry) following heat treatment (HT). Fractographic investigation revealed the formation of dendrites and hardening phases such as MgZn2 and Al2Mg3Zn3 among others, following HT. An alloy S10 recorded the peak ry of 117.200 MPa while S3 was the least with 51.212 MPa and extension (e) of 0.197 mm

Implementing electronic health system in Nigeria: perspective assessment in a specialist hospital

Background: Perspectives on the pioneering work of Electronic Health Recording (EHR) system in Nigeria was studied Objectives: To determine health workers perception, challenges, motivation and satisfaction with EHR. Methodology: This was a descriptive cross sectional study using structured questionnaire to assess health workers perspective on EHR system at Kogi State Specialist Hospital. Results: A total of 35 consenting health workers with an mean age of 39.4(\ub1 7.6) years using EHR were assessed. The mean daily work hour was 8.0(\ub1 2.4 hours) and median client load per participant was 20 daily. On perceptions, 74.3%, 52.9%, 45.5% and 60.0% were comfortable, well-motivated, satisfied and competent with EHR. The advantages were reduction in transcription cost (88.5%), Paper work (97.1%), administrative cost (91.4%), errors (82.9%) and it captures, provides more services including timely access and ease research in 94.3%, 74.3%, 94.3% and 82.9% respectively. Challenges were threat to patient privacy, poor internet, information overload, power outages, incomplete and inaccurate information in 17.0%, 65.7%, 31.5%, 62.9%, 37.1% and 22.9% respectively. Conclusion: Health workers were comfortable and satisfied with EHR and it eased their work.Scaling up EHR would reduce administrative cost, transcription errors and paper works to mitigate poor quality data from Nigeria a great contributor to global morbidities/mortalitie

Determinants of food demand among urban households in Minna Metropolis, Niger State, Nigeria

Agricultural products including rice, yam and cowpea play significant roles in the food consumption of urban dwellers. However, increase in crop production cost has continued to threaten urban food price in Nigeria. This study analyzed the determinants of demand for food commodities among urban households in Minna metropolis. Data were collected from 110 household heads of urban residences, which were selected through a three-stage random sampling technique. Data collected for the study were analyzed using multiple regression technique. The results showed that rice, yam and cowpea were price in-elastic. The cross-price elasticities for rice, yam and cowpea were -0.132, 0.028 and 0.005 respectively. The computed own price, cross price and income elasticity of demand for rice were –0.308, -0.132 and 0.018 respectively. For yam, the computed values were -1.262, 0.028 and 0.289 respectively. While for cowpea, these values were -0.530, 0.005 and 0.002 respectively. For the income elasticity, rice and cowpea were proven to be normal goods and yam as a luxury good. The social protection strategies in form of food aids policy should be put into action to minimize the inflationary pressure on food items in the urban areas

Carcase characteristics and meat quality assessments in goats subjected to slaughter without stunning and slaughter following different methods of electrical stunning

The study examined meat quality and carcase haemorrhage in goats subjected to different methods of pre-slaughter electrical stunning or slaughtered without stunning. Thirty-two Boer crossbred bucks were randomly assigned to low-frequency head-only (LFHO; 1 A for 3 s at a frequency of 50 Hz), low-frequency head-to-back (LFHB: 1 A for 3 s at a frequency of 50 Hz) or high-frequency head-to-back (HFHB; 1 A for 3 s at a frequency of 850 Hz) pre-slaughter electrical stunning or slaughter without stunning (SWS). All the 32 animals were bled to drain excess blood from the carcase. The slaughter was performed by a licenced slaughter man by severing carotid artery, jugular vein, trachea and oesophagus. At 12 h post-mortem, LFHO, LFHB and HFHB had lower (p < .05) glycogen and higher lactate and glycolytic potential values than SWS. A faster (p < .05) rate of pH decline was found in LFHO, LFHB and HFHB compared to SWS. No physicochemical parameters except cooking loss differed between treatments. Cooking loss was higher (p < .05) in LFHO, LFHB and HFHB compared to SWS at 7 and 14 d post-mortem. Incidences of carcase haemorrhages in electrically stunned goats were higher than SWS. Nonetheless, HFHB had lower (p < .05) haemorrhages than LFHB and LFHO. Electrical stunning prior slaughter increased carcase haemorrhages and cooking loss but did not affect other meat quality traits in goats